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PART I

BIS—ANNELATION OF ARENES VIA BIS-ARYNE
EQUIVALENTS; MECHANISM AND SYNTHETIC
APPLICATIONS

PART II

IETALLACYCLOPENTANES AS CATALYSTS
FOR THE LINEAR AND CYCLODIMERIZATION
OP OLEFINS

By

Shamouil Shamouilian

A DISSERTATION

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
DOCTOR OF PHILOSOPHY
Department of Chemistry
1981

AH ABSTRACT

PART I

(I "1 /1//

BIS-ANNELATION OF ARENES VIA BIS-ARYNE
EQUIVALENTS; MECHANISM AND SYNTHETIC
APPLICATIONS

PART II

METALLACYCLOPENTANES AS CATALYSTS
FOR THE LINEAR AND CYCLODIMERIZATION
OF OLEFINS

By

Shamouil Shamouilian

In the first part of this thesis bis-annelation of
arenes via bis-aryne equivalents was studied. Tetrahalo
arenes such as tetrabromo-p—xylene (g2) act as bis-aryne
equivalents upon treatment with n-butyllithium. The
aryne intermediate formed from this reaction was inter-
cepted with 2,5-dimethylfuran ($2) to give 9,10-dimethyl-

l,u,5,8-tetrahydroanthracene—1,h;5,8-bis-endoxide (£2)

Shamouil Shamouilian

as a mixture of syn and anti isomers. The mechanistic
routes to this bis-adduct were explored. The stepwise
process involves the mono-metalation of £2. Elimination
of LiBr generates the aryne which can be trapped with
diene $2 to form a mono-adduct. This mono—adduct can
subsequently go through the same process (metalation,
elimination of LiBr, and cycloaddition) to form 3%
(Path A). The other possibility is bis-metalation
of 32 which could directly eliminate two moles of LiBr
to give a bis-aryne intermediate which would be inter-
cepted by diene (Path B). Several experiments designed
to distinguish between Paths A and B were performed.
From the results of our experimental data we have conclu-
ded that this bis—annelation reaction proceeds stepwise
(Path A) and an aryne, not an organolithium compound,
is involved in the product-determining step.

The choice of solvent is important in this bis-
annelation reaction. Use of toluene as solvent made
it possible to control the reaction by the amount of
n-butyllithium used to synthesize the mono-adducts such
as l,A-dimethyl-l,A-dihydronaphthalene-l,A—endoxide (2%),
whereas ether or tetrahydrofuran as solvents always gave
32 no matter how much n—butyllithium was used. Mono-

adducts of this type were used to synthesize unsymmetric

bis-adducts.

II

al.

IL.

huh

t

 

Shamouil Shamouilian

Cyclopentadiene and its derivatives such as fulvenes
and spirocyclopentadienes gave very good yields of the
corresponding bis-adducts with novel structures. Several
experiments were performed to show that cyclopentadiene,
and not its anion, is required for this bis-annelation
reaction.

A simple one—step synthesis of triptycene analogs
prepared by the reaction of a bis-aryne equivalent with
anthracene is described. For example, 32, anthracene
and n-butyllithium gave 6,13-dimethyl—5,7,l2,lA-tetrahydro-
5,1A[l',2']: 7,12[l",2"]-dibenzenopentacene 22 (trivially
called a para-pentiptycene),

Several analogs of 33 were also prepared to show the
generality of the method. A,5-Dibromo—3,6-diiodo—o—
xylene (21) functioned as an ortho bis-aryne equivalent
to give, for example, with anthracene 6,7-dimethyl-
5,8,l3,1A-tetrahydro-5,1A[l',2']: 8,13-[l",2"]dibenzeno-
pentaphene (El) (trivially called an ortho-pentiptycene).
The synthesis of heptiptycene (5,6,ll,12,l3,18-hexahydro-
5-8[1',2']: 6,ll[l",2"112,l7[lm ,2” Jtribenzenotri-
naphthylene)(§g) has been improved and the intermediate
cycloalkyne (9,10-dihydro-9,lO-ethynoanthracene) has been
trapped with various dienes.

The technique of o-bis-annelation was extended to

a new and simple synthesis of phenanthrenes, particularly

Shamouil Shamouilian

applicable to hindered phenanthrenes. For example, the
reaction of 21 with N-(dimethylamino)tetramethylpyrrole
and n-butyllithium gave the corresponding bis-adduct
which upon pyrolysis resulted in the previously unknown
decamethylphenanthrene (lég). l,A,5,8,9,lO-Hexamethyl-
phenanthrene and 9,lO-dimethylphenanthrene were prepared
in a similar manner.

The application of this bis-annelation technique to
the synthesis of polyphenylarenes was explored. Bis-
adducts of 2,5-diphenylfuran or 3,6-diphenylisobenzo-
furan with bis-aryne equivalents could be aromatized
to give compounds with groups sandwiched between phenyl
rings. For example, 6,13—Dimethoxy-5,7,l2,lA-tetraphenyl—
pentacene was synthesized in this way.

In Part II of this thesis it is demonstrated that
metallacycles can play the role of catalyst for linear
or cyclodimerization of olefins. Cyclodimerization of
acrylonitrile to 1,2-dicyanocyclobutane using bis(tri-
phenylphosphine)tetramethylene Ni(II) as the catalyst

is described.

This thesis is dedicated to the memory of my father

Mosheh Shamouilian

ii

fit:

.I

-.
I.
‘7
‘
"s

ACKNOWLEDGMENTS

I wish to express my deepest appreciation to
Professor Harold Hart for his encouragement, guidance
and assistance throughout the course of this study.

Appreciation is extended to Michigan State Uni-
versity, National Science Foundation, and National
Institutes of Health for financial support in the form
of teaching and research assistantships.

Finally I would like to thank my brother Yousef
and my friend Sue for their continued help and encour-

agement in the past few years.

iii

TABLE OF CONTENTS

Chapter

LIST OP TABLES.
LIST OF FIGURES.
PART I - BIS-ANNELATION OP ARENES VIA
BIS—ARYNE EQUIVALENTS; MECHANISMS
AND SYNTHETIC APPLICATIONS.
Introduction.
Results and Discussion.
1. Mechanistic Studies of the Bis-
Annelation of Arenes via Bis—

Aryne Equivalents.

2. Bis-Annelation of Bis-Aryne

Equivalents with Cyclopentadienes.

3. Use of Bis-Aryne Equivalents in
the Synthesis of Iptycenes .

A. Application of Bis-Aryne Equiva—
lents to the Synthesis of
Phenanthrenes. . . . .

5. Polyphenylarenes: Groups
Sandwiched between Phenyl
Faces. . . . . . . . . .
6. Attempted Synthesis of N,N-
Bridged Bis-Aryne Equivalents:
Basket-Type Compounds. .
EXPERIMENTAL. . . .

1. General procedures.

iv

Page

.xii

xiii

18

3A

“9

6A

79

88

96
96

Chapter

10

11.

12.

Tetrabromo-p—xylene (25).
'L’L

Tetrabromo-p—xylene—d6
(£83536 ) '
l,“,5,8,9,lO-Hexamethyl-1,A,
5,8-tetrahydroanthracene-
l,A;5,8-bis-endoxide (29).

’V'b
2,5-Dibromo—A,6—diiodo-l,A-
dimethylbenzene (%§)'
2,S—Dibromo-A,6-dichloro—1,A-
dimethylbenzene (A7).

'b’b
2,3,5,6—Tetraiodo—l,A-dimethyl-

benzene (U8).
mm

l,A,5,8-Tetramethy1-6,7-dibromo-
l,A-dihydronaphtha1ene-
l,A-endoxide (31).

’V'b

1,A,5,8-Tetramethyl-9,lO-dimethyl-
d6-1,A,5,8-tetrahydroanthracene-
l,A;5,8-bis-endoxide (2%;d6).

Reaction of mono—adduct $1 and 2,5-

dimethylfuran with n-butyllithium.

Reaction of mono-adduct £1 and
tetrabromo—p—xylene (£23g6)

with n-butyllithium in the presence

of 2,5-dimethylfuran.

Reaction of £1 with n-butyllithium
in the presence of 2,5-dimethyl-
furan.

Page
97

97

98

99

99

.100

100

.102

.102

103

.ION

Chapter

13.

IA.

15.

16.

17.

20.

21.

22.

Reaction of £6 with n—butyllithium
in the presence of 2,5-
dimethylfuran.

Reaction of £8 with n-butyllithium
in the presence of 2,5—dimethyl-

furan.

N-Methyl-1,2,3,A,5,8—hexamethyl—
6,7-dibromo-l,A-dihydro-

naphthalene—l,A—imine (52).
’L’L

N—Nethyl-l,2,3,u,5,8,9,lO-octa-
methyl-1,A,5,8-tetrahydroanthra—

cene-l,A-imine—5,8-endoxide (§%)'

Bis—(N-methyl)—l,2,3,A,5,8,9,10-
octamethyl-1,A,5,8-tetrahydro-
anthracene-1,14 ;5 , 8—bis—imine (21;) .

1,U,5,6,7,10,1l,12—Octamethyl-
l,A,7,lO-tetrahydrobinaphthylene-
l,A;7,lO-bis-endoxide (22).

9,10—Dimethyl-1,A,5,8-tetrahydro-
l,A;5,8-dimethanoanthracene (16).

1,A,5,8—Tetrahydro-9,10-dimethyl-
11,12-bis(l-methylethylidene)l,A;
5,8—dimethanoanthracene (ll).

11,12-Bis(diphenylmethylene)-1,A,
5,8-tetrahydro-9,lO-dimethyl-l,A;
5,8-dimethanoanthracene 18.
1',A',5',8'-Tetrahydro-9',10'-
dimethyldispiro[cyclopropane-l,ll'-
[1,“;5,8]dimethanoanthracene-l2',ll"-

cyclopropane179.
'b’b

vi

Page

10“

105

106

.107

.108

.108

110

. 110

.111

Chapter

23.

2A.

R)
\JI

26.

27.

29.

30.

31.

32.

1',A',5',8'-Tetrahydro—9',10'-
dimethyldispiro[cyclopentane-l,ll'-
[1,A;5,8]dimethanoanthracene—
l2',1"-cyclopentane] 80.

’V'b
l,2-Dibromo-3,A,5,6-tetramethy1—
benzene (21).

'L’L
5,6,7,8-Tetramethyl-l,A-dihydro-
l,A-methanonaphthalene (81).
5,6,7,8-Tetramethyl—1,A—dihydro-Q—
(l-methylethylidene)-l,A-
methanonaphthalene (82).

’b’b
5,6,7,8-Tetramethy1-l,A-dihydro—Q—
(diphenylmethylene)-1,A—
methanonaphthalene (8%).
5',6',7',8'-Tetramethy1—l',A'-
dihydrospiro[cyclopropane-l,9'-
[1,AJ-methanonaphthalene] (8Q).
5',6',7',8'-Tetramethy1-1'U'-
dihydro—spiro[cyclopentane
1,9'-[l,A]-methanonaphthalene] (8%).
6,l3-Dimethyl-5,7,l2,lA—tetrahydro-
5,1A[l',2'J:7,12-[l",2"]-diben-
zenopentacene 86 (R = CH3).
6,13-Dimethoxy—5,7,l2,lA-tetrahydro-
5,1A[l',2']:7,12-[l",2"]-dibenzen-
opentacene 86 (R = OCHB).
6,13-Dihydroxy-5,7,l2,1A-tetrahydro-
5,1”[1',2']:7,12—[1",2"]dibenzeno-
pentacene 86 (R = OH).

vii

Page

.112

.112

.113

.113

11“

11A

.115

116

117

.118

Chapter

33.

3A.

35.

A0.

A1.

A2.

A3.

5,7,12,1u-Tetrahydro-5,1A[l',2']:
7,l2[l",2"]dibenzenopentacene-
6,13-dione (90).

mm
6,7,1“,lS—Tetramethyl-S,8,13,16—
tetrahydro-5,16-[l',2']:8,l3[1",
2"]dibenzenohexacene (92).
A,5—Dibromo—3,6-diiodo-o-
xylene (9i).
6,7-Dimethyl-5,8,l3,1A-tetrahydro—
5,1A[l',2']:8,l3—[1",2"]diben-
zenopentaphene 81 (R = CH3).

11-Chloro-9,10—dihydro-9,10—

ethenoanthracene (91)106.
N’b

ll-Chloro-12-deuterio-9,10—

dihydro-9,lO-ethenoanthracene (100).

12-Chloro—9,10—dihydro-9,10—
ethenoanthracene-ll—carboxylic
acid (99).

mm

ll-Chloro-l2-methyl-9,lO-dihydro-
9,10-ethenoanthracene (101).
’VVL

ll-Bromo-lZ-chloro-9,lO-dihydro-

9,10-ethenoanthracene (102).
WWW

5,6,11,l2,l7,l8-Hexahydro—5,l8[l',
2']:6,ll[l",2"]:12,17[1m ,2” Jtri—
benzenotrinaphthylene (88).

9,10[l',2'J-Benzeno-l,A-dimethyl-
l,A-epoxy-1,A,9,lO-tetrahydro-
anthracene (105). . . . .

WNW

viii

Page

119

.120

.120

.121

122

.123

.123

.123

.12N

12A

125

Chapter

AA.

“5.

A7.
A8.

1:9.

50.
51.

52.

53.

5A.
55.
56.

6,1l[1',2']-Benzeno-5,l2-dipheny1-
5,12-epoxy—5,6,ll,12-tetrahydro-
naphthacene (106).

'b'b'b

9,10[1',2'J-Benzeno-ll,ll-dimethoxy-
l,2,3,A,—tetrachloro-l,A-methano-
1,A,9,10-tetrahydroanthracene

(107).

mmm
9,10—Dimethy1-1,A,5,8-tetrahydro-
phenanthrene-l,“;5,8-bis—endoxide
127.

'VL’L

Hydrogenation of 127.
"VI/b

9,lO-Dimethylphenanthrene (129).
’L’b'b

1,A,5,8,9,10-Hexamethyl—1,A,5,8-
tetrahydrophenanthrene-l,A;5,8-

bis—endoxide 130.
’b’b’b

Hydrogenation of 130b (131).
'b’b’b'b 'b’b'b

Bis-(N—dimethylamino)-1,A,5,8,9,10—
hexamethy1-1,A,5,8—tetrahydrophenan-
threne-l,A;5,8-bis-imine (136).

’L'L'b

Bis(N-dimethylamino)-l,2,3,A,5,6,7,8,

9,10—decamethyl-1,A,5,8-tetrahydro-

phenanthrene-1,A;5,8-bis-imine (137).
'Vb'b

1,A,5,8,9,l0-Hexamethylphenanthrene
(132).

’V‘b'b

Decamethylphenanthrene (138).
’L’L’L

Reaction of 131 or 132 with RC1.
'L'L'L ’Vb’b

6,13-Dimethyl—5,7,12,1A-tetraphenyl-
5,6,12,1A-tetrahydropentacene—S,lu;
7,12-bis-endoxide 1A9 (R = CH3).

'b'b’b

ix

Page

.126

.127

.128
128

.129

130

.130

131

132

.132

133
.13A

.13A

Chapter

57.

58.

59.

60.

61.

62.

63.

6A.

65.

66.

6,13-Dimethoxy—5,7,12,lA-tetra-
phenyl-5,6,12,lA-tetrahydropen—
tacene-5,1A;7,12-bis-endoxide 1N9

’VL'L
(R = OCH3).

9,lO-Dimethyl-l,A,5,8-tetraphenyl-

1,4,5,8-tetrahydroanthracene-l,A;

5,8—bis-endoxide 150 (R = CH ).
mmm 3

9,10-Dimethoxy-1,A,5,8-tetraphenyl-

l,A,5,8-tetrahydroanthracene-l,A;

5,8-bis-endoxide 150 (R = OCH ).
mmm 3

6,7,1U,15-Tetramethyl—5,8,13,16-

tetraphenyl-5,8,l3,l6-tetrahydro-

hexacene-5,l6;8,l3-bis-endoxide 152.
'b'b’b

Reaction of 1A9 (R = CH3) with n-
’VL’L
butyllithium in the presence of

ferric chloride.

Reaction of 1A9 (R = CH?) with Zinc
’L’L’L .4
in Acetic Acid, (15A).
m m

Reaction of 1A9 (R = OCH3) with Zinc
'b’b’b
in Acetic Acid (15%).

Reaction of 25 with n-butyllithium
in the presence of dipyrrole 155

’b’b’b
(n = 3).

Reaction of 25 with n-butyllithium

in the presence of dipyrrole 155
(n = U).

Reaction of 25 and n-butyllithium
'b'b
in the presence of dipyrrole 155

’b'b'b
(n = 5). . . . . . . . . .

Page

136

136

.137

.138

.139

.1A0

1A0

.1A1

.1A2

.1A3

Chapter

67.

68.

PART II

Reaction of 25 with dipyrrole 155
'b'b ’VVL
(n = 5) and n-butyllithium

(attempted synthesis of 156).
'L'L'b

Reaction of 151 (n = 5) and
butyllithium (attempted synthesis
of 156).

“AA.

METALLACYCLOPENTANES AS CATALYSTS
FOR THE LINEAR AND CYCLODIMERIZATION
OE OLEFINS.

Introduction.

Results and Discussion.

EXPERIMENTAL.

1.

APPENDIX 1.

APPENDIX 2.

Bis(triphenylphosphine)nickel (II)

dichloride (160a).
N'L'L'b

l,A-di1ithiobutane (161).
’L’L'L

Bis(triphenylphosphine)tetramethyl-
enenickel (II) (162a).
'b'b’b’b

Tris(triphenylphosphine)tetramethyl-
ene NI(II) (164a).
"\fb’b’b

Cyclodimerization of acrylonitrile.

LIST OF REFERENCES.

xi

Page

1AA

.1A5

1A6
1M7
153
.157

.157
157

158

159
160

.162

.167
.173

LIST OF TABLES

Table Page
1. The Yield and SynzAnti Ratio of Eis-
adduct 29 from Tetrahalo-p-xylenes . . . . .19
mm
2. The Cycloaddition of a Bis-aryne

Equivalent with Cyclopentadienes. . . . . . A6

3. The Cycloadditon of Tetramethyl-
benzyne with Cyclopentadienes. . . . . . . A8
a. lBC-NNR Chemical Shifts (ppm) of 1:1

Adducts 157 (n 3,A,5) and 2:1
mmm

Adducts 158 (n = 3,“,5). . . . . . . . . . .93
xxx
1

H NMR Chemical Shifts (ppm) of 1:1
Adducts 157 (n 3,1,5) and 2:1
mmm
Adducts 158 (n 3,“,5). . . . . . . . . . .99

'V'b’b

Appendix 1. . . . . . . . . . . . . . . . . . . . . .162
Bond Distances (A) for 29b. . . . . . . . .16A
'b'b’b

Bond Angles (°) for 29b 165
'b’b’b
Appendix 2. . . . . . . . . . . . . . . . . . . . . .167
I Bond Distances (A) for 86 (R = OCH3). . . .169
'b

Bond Angles (°) for 86 (R = OCH ). . . . . 171
mm 3

xii

LIST OF FIGURES

Figure Page
1 Stereo drawing of bis-adduct 29b. . . . . . .17
'b’b’b
2 Stereo drawing of bis-adduct 86 (R = OCH3). .57
’b

xiii

PART I

BIS—ANNELATION OF ARENES VIA BIS-ARYNE
EQUIVALENTS; MECHANISM AND SYNTHETIC

APPLICATIONS

 

'r1
!

‘ .

i...»

 

INTRODUCTION
Benzyne (l)1 and activated alkynes (2) have very
'1; ’\:

similar reactions. Both exhibit the same tendency towards

polar addition and cycloaddition, butbenzyne(10 is by far

Ito—C:

I
O | nil (cufll
RO—é=0 U
I 2 3

the more reactive. This reactivity must be attributed to
the ring strain which results from lateral bending of the
bonds at the formal triple bond from the normal 180° found
in alkynes to be an angle close to 120° in benzyne. The
ground state energy of dehydrobenzene is thereby raised
relative to that of 2. Moreover, relief of angular
.strain during any reaction of benzyne will make the
reaction more exothermic and promote earlier attainment

of the transition state by the reactants. The combination
of these factors accounts for increased reactivity of

benzyne relative to g.

fl!

.1-

,1

rug

“V
\v.

Such an increase in reactivity with the introduction
of strain is readily recognized in a series of cycloal-
kynes (3). When n > 7 cycloalkynes are stable. Cyclo-
octyne (n = 6) can be isolated but it polymerizes
readily.2 Cycloheptyne has a lifetime of only a few
3

minutes at -20°C, whereas cycloalkynes with n equal to A
or 3 are capable only of transient existence and are very
reactive intermediates!4

5

In 1953, Roberts carried out decisive experiments to

test the participation of benzyne in the amination of

haloarenes. It was realized that if the amination of

Cl

@ »t" "Z

14
0 3 C label NH;

o

chlorobenzene with potassium amide in liquid ammonia did

 

 

 

   

NHa

proceed via benzyne as an intermediate, then the amination

of [1-1“

CJ-chlorobenzene should lead to equal amounts of
[l-luCJ-aniline and [2-1uCJ-aniline. This result was in

fact obtained.

Soon after, a new period in benzyne chemistrw'started.
Benzynes were trapped with different dienes in Diels-Alder
reactions.6 In a short time benzyne chemistry was pursued
in many laboratories. It received a great boost one
decade later when methods were found to generate benzyne
in the absence of organometallic agents.

The most widely used procedures for generating benzyne
from o-halogenophenyl anions are metalation of aryl halides
and metal-halogen exchange reactions on o-dihalogeno
aromatic compounds. Metal amides have been widely used as
metalating agents for aryl halides. Metalation of aryl
halides with organometallic compounds is a protophilic
substitution; thus the rate of this reaction in general
will increase with basicity of the metalating agent. This
rate for organolithium compounds decreases in the order
of t-butyllithium > isopropyllithium > n-butyllithium >
phenyllithium > methyllithium, while naphthyllithium or
anisyllithium are much weaker metalating agents.7

Generation of benzyne from o-halogenophenyl anions
depends on the nature of the halogen, because a carbon
halogen bond is broken in the loss of halide ion from A.
Ag can be prepared at -70°C by metal-halogen exchange
between 1,2-fluorobromobenzene and butyllithium, and may
be intercepted at temperatures below -60°C with carbon
dioxide, to give 2a in 88% yield.8 To effect the same
reaction with AR the temperature must be lowered to

—90°C. At that temperature a 93% yield of acid 22 was

C03H H
<— ——-> I
@ *(:02 @ 'liX @
X X

 

 

 

 

 

5 h- d b -
411 , I
50 ‘ 44a,)(=‘F 1 li CI
5c 4c,x:Br
46b
‘ CO2
(Kbgi c|

obtained, but if the solution was warmed to -60°C prior to
carboxylation 6b was formed and trapped as the acid in 17%
yield.8 If similar reactions are tried with 2-bromophenyl-
lithium Ac, even a temperature of -100°C is not low enough
to stabilize the anion. Immediate carboxylation after
preparation of 2-bromophenyllithium by metal halogen
exchange at -100°C gave only 23% of 5%; after A5 minutes
none could be obtained at all.8 At -130°C, however,
2-bromophenyllithium has been trapped in reasonable yield

with chlorodiethylphosphine.9

~\\
I \

SVFL

Wittig,6 in 1955, was the first to trap benzyne in a

Diels—Alder reaction. The benzyne was generated from o—
fluorobromobenzene and lithium amalgam in the presence of

furan as a trap. This reaction became so characteristic

 

F Lng)
@ .‘L" l * {‘1

7

 

 

that it now serves as a diagnostic test for the formation
of benzyne from various precursors. Because of their
thermal stability, anthracene and tetracyclone have
become standard reagents for trapping benzynes generated
at elevated temperatures.10

Many of these reactions have considerable preparative

value. For example, 1,A—dihydronaphthalene—l,A—endoxide Z

 

is readily converted into a-naphthol 8 or naphthalene

ll
9. Decarbonylation occurs during the reaction of

benzyne with tetracyclone, giving rise directly to tetra-
phenylnaphthalene 12.12 Annelation of two aromatic rings

can be achieved by cycloaddition of diphenylisobenzofuran

 

 

 

Ph 7' o ‘
Ph ”I
I '0' O G _> Ph
Ph
Ph Ph Ph J
- CO
I”!
N!
@@
Ph
Ph
‘0

to benzyne, since the resulting adduct 11 can be deoxy-
genated either thermally or with metallic zinc to give
9,10-diphenylanthracene 12.13

Wadi—“L

'I'I
Zn; 882!
Ph
Ph
12

A simple synthesis of triptycene 13 was achieved by
A
Wittigl' through the cycloaddition of benzyne to anthra-
cene. A large variety of dienes, such as cyclopenta-

15 16 17

diene, dimethylfulvene and N—substituted pyrroles

have been used in similar processes.

@I + @©@ “4

ai.‘

ha

Arynes have been used in the synthesis of polymethyl-
arenes such as decamethylanthracene18 and octamethylnaphth—
alene.19 The synthetic challenge arises from the need to
introduce peri-interacting groups, such as the methyls,
at the 1,8 positions in naphthalene or at the 1,A,5,8,

9,10 positions in anthracene. Substituents located at
these positions are in much closer proximity than similar
substituents located at ortho positions. Octamethyl-
naphthalene contains two peri methyl interactions and
decamethylanthracene contains four such interactions.
Therefore these molecules are strained relative to the
nonsubstituted ones. This strain induced special reac-
tivity in these compounds. For example decamethylan-
thracene (IA) is unstableixiacidic or basic media and it

will rearrange (1,5—hydrogen shift) to the hydrocarbon

tautomer 15 in which the central ring is not aromatic, to

18

relieve this strain.

 

   

are/:0

3 § fv

.L‘
....n

10

Decamethylanthracene was first synthesized in our

18

laboratory as follows:

Br CozH—d 15d I) [AH @©
2) A
8' 2Cl

13
16 ?u

N
S\ [Z "-80“

 

 

©©© ‘ 11:3:

14

 

Diazoniumcarboxylate 16 was used as the aryne precursor in
the first step. Reduction of adduct 17 and pyrolysis of
the reduced product gave dibromonaphthalene 18, which was
used as a second aryne precursor in the next step. Treat—
ment of 18 with n-butyllithium in the presence of pyrrole
12 formed cycloadduct £0. Removal of the nitrogen bridge
was achieved by oxidation with meta-chloroperbenzoic acid

(mePBA) to give 1A. This synthesis was designed to
’b

gradually introduce the peri-interactions and also to

11

compensate for some of the resulting strain energy by
other energy-releasing processes (i.e., aromatization).
Both cycloaddition steps are exothermic because
arynes are high energy intermediates. The bridge removal
steps, which introduce the peri-strain, are accompanied
by the formation of an aromatic ring. This aromatization
energy compensates for some of the energy introduced in
the molecule because of the peri-interacting groups.
Also note that the last step in this sequence occurs under
essentially neutral conditions which prevents rearrange-
ment of the decamethylanthracene.
This strategy also was used to synthesize octa-

methylnaphthalene in excellent yield.19

*Br n-Buli
4
@ + mr -7a’c
Br
I
21

22

 

 

m-CPBA

©

24

 

$...
v".

“(‘1‘
ca;

‘1)
(3‘

(f)

 

12

Looking back at the synthesis of decamethylanthra-
cene, the strategy was to start with one of the benzene
rings and construct the other two in separate steps from
cycloaddition of the arynes to the proper dienes. It
was thought that this synthesis could be shortened to
two steps by constructing the two benzene rings simultane-
ously; therefore a properly functionalized benzene was
sought.

It seemed that tetrabromo-p-xylene could function as
a bis-benzyne precursor or its equivalent upon its reac-
tion with n-butyllithium. Thus, when a mixture of
tetrabromo-p-xylene (25) and pentamethyl pyrrole (22)
was reacted with n-butyllithium at -78°C under argon, a
78% yield of the expected bis-adduct 26 was obtained.
Subsequent excision oftfimenitrogen bridges gave decame-
thylanthracene in good yield (Scheme 1). Successful
accomplishment of this idea substantially increased the
overall yield of 1A.

Several possible mechanistic routes can be considered
for the formation of bis-adduct 26. Several experiments
designed to determine the mechanisms whereby bis-aryne
equivalents such as 25 function were performed. Discovery
of toluene as an appropriate solvent for this reaction
permitted synthesis of the corresponding mono-adducts.

Use of these mono-adducts as benzyne precursors ixlreactions
similar to that shown for 22 gave cross bis-adducts in

which the two new annelated rings need not be identical.

 

§L= \

. U

13

 

 

Scheme I
St Bf n - Buli
?
+ I \ other . - yg'c ”.0 a
3' 3' "l‘ ' 78x
25 22 26
m-CPBA
50%;
N¢12CO3
V
14

Subsequent bridge removal from these cross bis-adducts
would result in unsymmetrically substituted anthracenes.

In our further attempt to explore the scope of this
bis—annelation technique, a variety of dienes were used.
Cyclopentadiene, fulvenes and spirocyclopentadienes all
gave bis-adducts with novel structures in good yields.
Use of 2,5-diphenylfuran or 3,6-diphenylisobenzofuran in
this bis-annelation reaction was explored, and could be
considered as a simple entry to polyphenyl substituted
arenes such as anthracene or pentacenes. Bis-annelation
of bis-aryne equivalents with anthracene gave a very simple
entry to a whole new classcflicompounds for which the name
"iptycenes" is proposed.

This bis-annelation technique was also extended to

angular rather than horizontal bis-annelation by using

1A

the properly substituted tetrahalo arene. Application of
this angular bis-annelation led to a new and simple synthe-
sis of phenanthrenes. Dienes such as dipyrroles have also
been used in this bis-annelation reaction in an attempt

to synthesize N-N bridged bis-adducts (basket type
compounds). The main part of this thesis describes

mechanistic and synthetic studies on bis-aryne equivalents.

15

RESULTS AND DISCUSSION

The reactions between benzyne and selected dienes

 

have been used to annelate benzenes. For example,
I +(/\1~ +0
X.
27
-.X

00

The first step is a [2+A] cycloaddition to give the adduct
27; in the second step the X-bridge is eliminated in some
way, thus producing a second aromatic ring fused to the
benzene ring of the benzyne precursor.

Some time ago we thought that mono-annelation of
benzyne with dienes could be extended to bis-annelation
simply by using a properly functionalized benzene which
in effect would function as a bis—aryne precursor. The
first experiments, which were carried out by Dr. Chana

20

Zlotogorski, showed that this idea was feasible, and

the application of this idea to the synthesis of

16

decamethylanthracene has already been described (Scheme
1, p. 13).

We have also used 2,5-dimethylfuran as a diene in
a similar bis-annelation reaction. When a suspension
of tetrabromo-p—xylene (£5) and 2,5-dimethy1furan (28)
in ether at -78°C was treated with n-butyllithium under

argon, a 78% yield of bis-adduct 29 was obtained.
’b":

Br

 

25 28 29

This bis-annelation reaction was expected to produce two
isomers of bis-adduct 29, the syn isomer, in which the two
oxygen—bridges are both on the same side of the plane

of the benzene ring (29%), and the anti isomer, in which
one oxygen-bridge is above and the other is below the

plane of the benzene ring (29b).
. _ WNW

c) C)
\\@U
Syn

290 295

 

 

r)

'1

{—J

 

17

Figure I

 

The proton NMR spectrum of bis-adduct 29 clearly showed
the presence of these two isomers. The major isomer
showed singlets at 6 1.93 (12 H, bridgehead methyls),
2.28 (6 H, aromatic methyls), and 6.78 (A H, the vinyl
hydrogens), whereas those of the minor isomer were at

5 1.95, 2.3A and 6.75. In order to determine the ratio
of these isomers in the reaction product, the area
ratio in the lHNMR spectrum signals at 180 MHz of the
crude reaction product were measured. A ratio of 57:A3
was obtained. Spectroscopic data such as NMR, mass,

IR and UV were not able to distinguish which isomer was
which; thus, we used X-ray crystallography. A pure
sample of the major isomer was obtained by repeated
washing of the crude product mixture with ether, and
crystallization from acetonitrile. The X-ray crystal
structure of the isomer determined that the oxygen
bridges were anti. Figure 1 shows the stereo drawing of

this anti isomer. In Appendix 1, tables of the bond

distances and the bond angles are given.

he: v.

1.

,
\1r
~‘...

A..
.—

.4...

‘r~

u..-

? L y:n

s... .

. l :

”-a.

1
.§

"a¢.,

"
”CA.
“5“-
b" A.

-
‘lv‘bl
.-

1- '
v; I
q.
'I
§' .
F: |
A.” u
1 o ‘
i 1 'r-
~‘&.‘.‘
s.
l" r
i‘L. .1
"JR
i n p
‘ a

{531+
5“”

18

l. Mechanistic Studies of the Bis-Annelation of Arenes

 

via Bis-Aryne Equivalents.

 

Several pathways can be considered to explain the
formation of the bis-adduct 29, and several experiments
were performed in order to explore these possibilities.
Scheme 2 shows some of these possible paths.

Path [A] is a stepwise process involving mono-
metalation of 25. Elimination of lithium bromide generates
the aryne which can be trapped with diene 28 to form the
mono-adduct 31. This mono—adduct can subsequently go
through a similar process (metalation, elimination of
LiBr, cycloaddition) to form the bis-adduct 29. On the
other hand, bis-metalation of 25 would resultmin inter-
mediate 3A. This intermediate might either lose two
moles of LiBr simultaneously to generate the bis-aryne
35, which could be trapped with 2,5-dimethylfuran togfive
the bis-adduct ’29,, or the two equivalents of LiBr could be
eliminated stepwise to first give 32 and then give 29.

One of the other possibilities is that this reaction
may not proceed through aryne intermediates, but rather
via organo lithium compounds such as 32 or 3A, which
react directly with the furan.

The first experiment performed in order to distinguish
between Path A or B was to react 1 equivalent of tetrabromo-
p-xylene (£2) with only 1 equivalent of n-butyllithium.

If this reaction proceded stepwise, we would expect to

obtain only the mono-adduct 31. The result showed that

Scheme 2

 

 

20

bis-adduct 22 was the only reaction product, plus some
unreacted 25. No trace of mono—adduct 31 was observed.
This result is somewhat similar to Wittig's,21 who found
that whereas the reaction of dibromodifluoro-p-xylene
(36) with furan and magnesium in refluxing THP gave
mainly the mono—adduct 37 (3A%) and 5% of the bis-adduct
38, n-butyllithium gave only the bis-adduct 38 in 15%

yield. Wittig concluded, because he isolated mono-adduct

Br F Mg] THF
)-
Furan

 

 

F Br or
n-Buli
36 37 38
M9 ; 35; 5::
0-30“; 0% 15X

37 in the magnesium reaction, that the reaction is
stepwise. But formation only of bis-adduct 22 when
n-butyllithium was used is also consistent with Path B,
which involves bis-metalation.

Bis-arynes have been postulated as intermediates in
the mass spectral fragmentation of pyromellitic (39)
or mellophanic (Ag) dianhydrides. Both 39 and AB showed
an intense peak at m/g 7A (about 60%) which was explained
by formation of the corresponding bis-aryne fragments Al

and A2 respectively.22
’Vb

21

O 0 o
o o o
o 0 ° 0
o

39 ° 40
+ +

IOI OI

‘\
41 42

The cyclic structure of these fragments was not proven.
Bis-arynes were also used to rationalize the products

formed from the copyrolysis of benzene with 39 or A0.22

mm WW
Scheme 3 shows the products derived from the pyrolysis of
Ag. Phenanthrene (A3) may be formed by two l,A-additions
of bis-benzyne to benzene; phenylnaphthalene (AA) can
result from an addition and an insertion; and terphenyl
(Ag) may be formed from two insertions. Although bis-
benzyne A2 as an intermediate would account for the

formation of these products, other explanations, such as

stepwise formation of these products, are possible.

22

 

Scheme 3
o
0
° 0
o
o
4!)

 

 

 

.45

In our effort to investigate the reaction mechanism
of the bis-annelation of arenes, we designed experiments
to distinguish between Paths A and B, as follows:

a) In order to determine whether arynes or organo-
lithium compounds are involved in the product-determining
step, a variety of arenes such as dibromodiiodo (Ag),
dibromodichloro (AZ) and tetraiodo (£8)-p-xylenes were

synthesized. These arenes were readily accessible from

23

commercially available starting materials, often in only
one or two steps. Tetrabromo-p—xylene was prepared in
90% yield according to the literature method23 by adding
excess bromine to p-xylene in the presence of iron powder
at 0°C. Tetraiodobenzene (:8) was prepared in good yield

2“ method by mercuration of p-

according to Yagupolskii's
xylene with trifluoromercuriacetate, and iodination of
this mercury compound with I2/KI. Dibromodiiodo—p-
xylene (A6), which was not a previously known compound,
was prepared in 89% yield by dropwise addition of bromine
to a solution of l,A—dimethyl-2,5-diiodobenzene and ferric

chloride in nitromethane at 0°C.

 

 

3 IF Cl
0 22143::0: D» 0

Br I

46

Compound AZ was synthesized in 5A% yield by passing C12

gas through a solution of l,A-dimethy1-2,S-dibromobenzene

 

and ferric chloride in nitromethane.25
3' cu n! cu a: a
O -——c’.. 50’ 1. 0
Br ’ ’ c| Br

47

2A

With the use of these arenes in a similar reaction
to that used for 25, one would expect, if the bis-
annelation reaction proceeds through common intermediates
such as aryne 33 or bis-aryne 32, a similar anti:syn
ratio of the products in all cases. However, if organo-
lithium compounds such as 31 or 33 were involved in the
product-determining step (since carbon—halogen bond
cleavage is involved in this step), the anti:syn ratio
would be expected to vary depending upon the tetrahalo
arene used. Table 1 compares the yield and the anti:syn
ratio of the bis-adduct 29 which was formed from bis-
annelation of these tetrahalo arenes with 2,5-dimethyl-
furan.

Our experimental results showed that these ratios
are similar (57:A3) except for tetraiodo-p-xylene;
thus we believe that arynes have been formed in the

product-determining step, and we can rule out the

involvement of organolithium compounds in this step.

Tetraiodo-p-xylene gave a slightly different
anti:syn ratio (61:39). Although we have checked this

ratio accurately, it could still be within the experimental

25

TABLE 1

The Yield and SymAnti Ratio of Bis-

adduct 29 from Ietrahalo-p-xylenes

 

Arene Yield of Bis-adduct

Anti :Syn Ratio

 

78%

76%

35%

68%

 

 

 

57:43

57 =43

57 :43

61:39

26

error. It is also possible that intermediates such as

A}, and 50 could be involved in the case of the tetraiodoarene.

O 0

[1 l l

49 50

b) If this bis-annelation reaction in fact proceeds
stepwise through the formation of mono-adduct 31 (Path A),
reaction of this mono-adduct with n-butyllithium in the
presence of 2,5-dimethylfuran should result in the
formation oftflmebis-adduct 29 with the same anti:syn
ratio as for the bis-adduct formed from tetrabromo-p-
xylene. In order to check this, the mono-adduct 31 was
synthesized independently. When a suspension of
diazonium carboxylate 21 and excess of 2,5—dimethylfuran
was heated at reflux in 1,2-dichloroethane a 71% yield of
mono-adduct 31 was obtained. The proton NMR spectrum of

31 shows singlets at 6 1.98 (6 H), 2.A8 (6 H), and

B, CO; Cl-CHa-CH; Cl Br
. I \ a» .
3 N; Q Reflux B O m

51 28 31

 

27

6.77 (2 H). The anthranilic acid corresponding to 51
was made according to Hart and Huge.18

When one equivalent of the mono-adduct 31 reacted
with one equivalent of n-butyllithium in the presence of
an excess of 28, a 98% yield of bis-adduct 29 was obtained

with the anti:syn ratio (57:A3).

1 equim n -Iuli
4- I I.»
e O I} 9’ * 1 O

31 2B 29

 

This result supports the stepwise process (Path A), but
it does not rule out the bis-metalation (Path B) as a
competitive route.

c) A deuterium labeling experiment was designed as
follows, which was expected to distinguish Path A from
B. If a mixture of mono-adduct 31 and labeled tetrabromo-
p-xylene (£2Eg6)’ one equivalent of each, were allowed to
react with n-butyllithium (2 equivalents)in the presence
of 2,5-dimethylfuran, and if the reaction proceeded
through bis-metalation, the reaction product would be
expected to contain a mixture of labeled and unlabeled
bis-adduct £2 and some unreacted starting materials. If
however, the reaction proceeded in a stepwise manner,

the reaction product not only should contain bis-adducts

28

29 and 29—d6, but also should contain labeled mono—adduct
’b 'b’b'b

31 as well (Scheme A).
NW

 

Scheme: 4
C05
Br Br Br
- 03 o + [1
Br Br Br 0
CEH
n-BuU
(co,) (CD3)
CH, CH;
Br
0 . + 0
Br
CH3 CH3
31+31-d6 29+29 -d6

Tetrabromo-p-xylene-d6 was prepared in almost

quantitative yield by bromination of p-xylene-d When

10'
88E86 was treated with n-butyllithium in the presence of

2,5-dimethylfuran in a similar manner as for $5 a 98%

29

yield of bis-adduct 29-d6 was obtained, as a mixture of
mmmm

two isomers. The proton NMR spectrum of 29—d6 clearly
'VVVL

shows the absence of the 9,10-methyl signal in 22.

 

co, co,
3' Br n -Bu U
o + Q :» 0
Br Br
co, co,
25 «I, 29 «a

In another experiment, a mixture of 32:86 and 31
(0.5 equivalents of each) was allowed to react with 1
equivalent of n-butyllithium in the presence of excess
2,5—dimethylfuran (ether, -78°C). In addition to a
58% yield of a mixture of labeled and unlabeled bis-
adduct 29 and a 26% yield of unreacted 25:36, a 17%
yield of mono-adduct 31 was separated by column chroma-
tography. This mono-adduct contained 30-AO% deuterium
in the aromatic methyls. The presence of deuterium in
the mono-adduct 31 was established from its proton NMR
spectrum, in that the signal corresponding to the aromatic
methyls (61.98 ppm) did not integrate equally with the
signal at 62.A8 (bridgehead methyls) and was about
30-A0% smaller. Also,the mass spectrum of this mixture
showed a triplet centered at m/g 363 which is six mass
units higher than the triplet observed for M+ of the

non-labeled mono-adduct 31. The presence of 8%336 in

30

the reaction mixture clearly proves that the bis-annela-
tion is stepwise (Path A).

Tetrabromo-p-xylene is a highly symmetric compound
with very low solubility in ether at -78°C (about 300 mg
in 100 mL). Most of it precipitates out when the
reaction mixture is cooled to —78°C. On the other hand,
mono-adduct 31 is less symmetric and contains functional
groups such as the ether bridge and the double bond.
Thus it is much more soluble in ether at —78°C than the
starting tetrabromo—p—xylene. We suspected that because
of this greater solubility, 31 would react preferentially
with the n-butyllithium. Thus, regardless of whether
one or two equivalents of n-butyllithium were used,
the product would always be the bis-adduct 29.

A better solvent for tetrabromo-p-xylene was therefore
sought. THF gave the same result as ether. But when
toluene was used as the solvent in the synthesis of
bis-adduct 29, the yield was increased from 78% to 93%.
Also, with toluene as solvent, when only one equivalent
of n—butyllithium was used, mono-adduct 31 was obtained
in 95% yield (it had the same physical constants as
21 which was prepared independently). The fact that by
changing the solvent to toluene an almost quantitative
yield of mono-adduct 31 was obtained is further evidence
to prove that the reaction does not proceed through

bis-metalation competing with the stepwise process.

 

'7’.

(1‘

(I)

Fl)

l\)

__>

31

From the results of these experiments we conclude
that bis-aryne ($2) is not an intermediate in the reaction.
However since the products are those which would be
obtained if a bis-aryne were an intermediate, we call
the tetrahalo arene precursors bis-aryne equivalents.

Discovery of toluene as a solvent not only increased
the yield of the bis-adducts in most of the reactions,
but also made possible the synthesis of mono—adducts
such as 2%. In a similar procedure as for él, when a
solution of $2 (1 equivalent) and pentamethylpyrrole
$3 (1 equivalent) in toluene was reacted with n-butyllithium

(1 equivalent), an 88% yield of mono-adduct 52 was obtained.
NW

3' 3' n -Bu l.i
::ll:iil[: ‘* 4/2[::§&\. Toduoni.*
Br Br I _ 78'C

25 22 52

 

 

The fact that these mono-adducts could be synthesized
in good yields added versatility to this bis-annelation
in that the two new fused rings could be different from
one another. Thus, unsymmetric bis—adducts 2% and 23

were synthesized (Scheme 5).

32

Scheme 5
Br
0 *
Br
31

 

O ‘11 5.

Br

52 28

 

 

Such unsymmetric adducts are not only novel compounds
themselves, but one could also use standard methods to
remove the nitrogen or oxygen bridges to obtain unsym-

metrically substituted anthracenes.

33

The mono-adducts could also be used to synthesize
binaphthylene derivatives such as 22. For example, when
a solution of 2% in toluene at -78°C under argon was
treated with n-butyllithium, an 8-10% yield of 3% was
obtained as a mixture of syn and anti isomers. No

attempt was made to optimize the yield.

o moo-o

31 55

Dr n-Iuli
:>-

 

Br

   

Compound 22 presumably was formed by the [2+2] cyclodi-
merization of the aryne intermediate.26

In conclusion, experimental data have been provided
which prove that the bis-annelation of £2 occurs in a
stepwise manner through the mono—adduct 2%, rather than
through bis-metalation and bis-aryne (3%). Also, it was
established that arynes, rather than organolithium com-
pounds, are involved in the product-determining step.
The stepwise nature of this bis-annelation reaction was
used in the synthesis of unsymmetric bis-adducts such as
2% and 23, which could be considered as precursors for

unsymmetrically substituted anthracenes. Mono-adduct 31
mm

was also used to synthesize a binaphthylene derivative

(55).
mm

3H

2. Bis—Annelation of Bis-Aryne Equivalents with Cyclo-

pentadienes.

 

Meinwald and coworkers27 were the first to synthesize
benzonorbornenes (I). The choice of this name was
motivated bytflmedesire to relate this sytem to the
parent compound norbornadiene (II); however the Ring
Index would designate this system as a l,h-dihydro—

1,u-methanonaphthalene (III).

9

   

The starting material for this synthesis was the well
known lzl cyclopentadiene-quinone adduct 2g.28 Treatment
of 32 with acetic anhydride and pyridine gave the expected

diacetate 21 in excellent yield.

35

 

(DR
(3
.Ac2C>
fl a»
Pyridine
c) (3R
R=COMe
56 5 7

Later, Wittig15

used benzyne to synthesize the parent
compound 3%. When a solution of o—fluorobromobenzene
and cyclopentadiene in dry THF reacted with Mg, a 66%

yield of QR was obtained. This elegant procedure made

0 +

 

 

53 59 60

benzonobornene QR readily available. Shortly afterwards,
Bartlett29 used this compound as an intermediate in the
synthesis of benzo analogs of endo-, exo- and 7-norborne-
nol, to study their rates of solvolysis.

Compound g8 has also been synthesized in NO% yield
by the same strategy by using benzenediazonium carboxylate

30

as the benZyne precursor.

36

31 32

Huisgen and Wittig, in their studies of nucleo—
philic aromatic substitution reactions (for example the
reaction of n-butyllithium and o-halobenzenes), concluded
that the formation of benzyne occurs in two steps: the
metalation and subsequent elimination of metal halide.
Huisgen31 proposed that the rate-determining step was
generally the metalation reaction, and that the rate of

elimination of halogen anions occurred in the order of

iodine > bromine > chlorine >> fluorine. Later, Tanida

et a1.16 studied the formation of benzynes from several
o-dihalobenzenes. The arynes were intercepted by cyclo-
pentadiene. From these studies Tanida concluded that met—
alation or elimination could be rate—determining, depend-
ing upon the particular case. For example reaction of 2,5-
dibromo-l-iodobenzene with cyclopentadiene and magnesium
not only produced the desired 6-bromo-l,D-dihyro-l,u-
methanonaphthalene, but also a considerable amount of
p-dibromobenzene and 3-bromoiodobenzene were formed.
Formation of the last two arenes suggested that the
metalation reaction took place without the subsequent
elimination, whereas the reactioncfi‘arenes such as
u-bromo-3-iodoanisole, 3-bromo-U-fluorobenzene or
2-bromo-U-chlorobenzene with cyclopentadiene and
magnesium gave only the desired cycloadduct. Therefore

Tanida suggested that Huisgen's discussions and Wittig's

findings are probably valid in terms of their own

37

experiments and that which step is the rate-determining
step depends primarily upon the particular case.

In general, bicyclo[2.2.l]heptanes and other compounds
with this skeleton have received wide attention. They
often have been employedix1the development of modern
organic theories because of their special fixed stereo-
chemistry and the high strain of the ring system.

Extensive studies have been done on both the thermal and
photochemical rearrangements of benzonorbornadiene.
Pyrolysis of $2 at 370-380°C forfiul h resulted in an

§5% conversion to 61.33

’L’b

373-3362

O .. t”

60 6]

 

Deuterium labeling studies suggested that the rearrange-
ment possibly goes through intermediates such as gig

or 61b or both.33
'b'b’b

4
ID

61¢ 61!:

38

The photoarrangement of fig has also been explored

 

ab 52:.» a ‘5‘

6° 62

3U

extensively. Prolonged direct irradiation did not
appear to give any 32, while acetophenone sensitization
gave good conversion. The mechanism of this photoprocess
(di—n-methane-rearrangement) has been established.35
Benzonorbornadiene QR has also been widely used in
organic synthesis, a few examples will be mentioned in
order to further demonstrate the applications of such
36

a system. Tanida and coworkers used norbornadienes
and their derivatives acting as dienophiles toward

dienes such as tropone and 9,10-dimethylanthracene, in
order to study the participation of non-conjugated double
bonds in the Diels-Alder reaction. For example, adducts

such as 63 and 6“ were prepared.
’Vh ’b’b

39

 

Mitsudo37

showed that $2 readily reacts with an equimolar
amount of dimethyl acetylenedicarboxylate in the presence
of a ruthenium catalyst in benzene at 80-lOO°C to give

the corresponding [2+2] cross-adduct 22.

COIM.
l CCkkM:
C In cat.
0 ——~@ by
<II 67" co,Me
co
60 ’M‘ 65

Compound 60 has also been conveniently used in the
mm

large-scale preparation of benzobarrelene (67) through
mm

its dichlorocarbene adduct éé.38

68

U0

 

a b :3» a

60 66 ”

Cl

3sfleps
BSZL

O

67

Cycloadducts of benzyne with substituted cyclopen—
tadiene systems such as 6,6-dimethylfu1vene (QQ), spiro
[M,2]hepta-N,6-dienes (12) and spiro[u,u]-nona-l,3-diene
(1%) have been prepared.

68 69 7O 7]

M1

39 because of an interest in the

Tanida and his coworkers,
homobenzylic behavior observed at the 7—position of
benzonorbornadiene derivatives, synthesized 7-isopropyl-
idenebenzonorbornadiene (12) in 31% yield through
cycloaddition of benzyne generated from o-bromofluoro-

benzene and magnesium with $2. The cycloadduct of benzyne

and fulvene was also prepared in low yield“0 and used in

F I
o o mpg

68 72

 

the synthesis of isobenzofulvene.l41 Compound Z2 was
'b

36 as a dienophile in a similar Diels-Alder

H2

used by Tanida
reaction to that mentioned for £8. Sasaki and coworkers
. very recently reported regio and stereo selective cyclo-
addition reactions of Z2.

In order to study the effect of cyclopropyl conju—
gation on the photochemical isomerization of divinyl

“3 investigated the direct and

methane systems, Trost
sensitized irradiations of spiroEcyclopropane-l,9'-
l',h'—dihydro[l,fljmethanonaphthalene] 13. This compound
was prepared in 63% yield by the addition of benzyne

to 70.
mm

N2

 

@212:

70

 

74

Irradiation of a 1% solution of 1% in ether containing

0.01% acetophenone gave a 65% yield of 13. These results,

which are analogous to those obtained with 62 (p. 38),

indicated that the cyclopropane ring has no effect on

the course of the reaction.
Spiro[cyclopentane-l,9'-l',U'-dihydro[l,u]methano-

naphthalene] (12) was also prepared by Wittig's method.uu

C

 

on; .

71 75

43

In light of all the known chemistry of the benzonor-
bornadiene system, we thought it would be worthwhile to
extend the bis—annelation reaction with bis—aryne equiva-
lents to cyclopentadienes. Not only would it be possible
to obtain a variety of novel bis-adducts but they could
be useful as intermediates in similar studies to those
mentioned for 60.

’V‘U

One might possibly think that the use of n-butyllith-
ium to generate arynes would not be compatible with dienes
having strongly acidic hydrogens, such as cyclopentadiene.
Therefore, the first attempt to bis-annelate with cyclopen-
tadiene was done using excess n-butyllithium, in order to
accomodate formation of the cyclopentadiene anion. A
solution of tetrabromo-p—xylene (22) (1 equivalent) and
cyclopentadiene (2 equivalents) in ether was cooled to

-78°C under argon. Four equivalents of n-butyllithium

(two to react with the bis-aryne equivalent and two to

react with the cyclopentadiene) were added dropwise in

2 h, and the reaction mixture was allowed to warm slowly

to room temperature. After work-up a 37% yield of bis-

adduct £6 was obtained as a mixture of anti and syn

isomers.

lH-I

Br
0 Br fl-Bull
+ ther.
Br Br 9 -78 C

25 59 76

 

All experimental data were consistent with the structure
(1H and 13C NMR spectra and mass spectrum).

To determine whether cyclopentadiene or its anion was
involved in the cycloaddition reaction, the above
experiment was repeated as follows. Equimolar amounts of
cyclopentadiene and butyllithium were allowed to react at
-78°C in ether. Thus all the cyclopentadiene was converted
to its anion, which precipitated. Then the bis-aryne
equivalent, tetrabromo-p-xylene, was added followed by
2 equivalents of n-butyllithium (to generate the aryne).
On work up only polymeric material and cyclopentadiene
dimer were obtained. No trace of bis-adduct 16 was
observed. Thus it is clear that free cyclopentadiene,
and not its anion, is essential for the cycloaddition.

The result of this experiment, combined with the

first experiment, suggests that metal—halogen exchange

“5

on the benzene ring occurs faster than proton removal
from cyclopentadiene. The first experiment was therefore
repeated under the same conditions but using only two
instead of four equivalents of n-butyllithium. After
work up an almost quantitative yield of 16 was obtained.
Thus excess n-butyllithium was actually dgtrimental,
since it removed some of the cyclopentadiene from the
reaction.

Cyclopentadienes 23-1% were also used to synthesize
bis—adducts 11-22 (Table 2). In all cases the reaction
product contained a mixture of anti and syn isomers.

Often one of the isomers was obtained pure by trituration
of the crude product with hexane or methanol. The
remaining hexane or methanol solution was later concentra-
ted and the resulting solid was chromatographed on
activated alumina to obtain a pure sample containing a
mixture of the two isomers. A great effort was not put
forth to completely separate these isomers. The 1H NMR,
13C NMR and mass spectra of adducts zz-ég are quite
similar to those of bis-adduct 16.

The butyllithium technique for generating benzynes
was also used to synthesize the tetramethyl derivatives
of 60, 72, 73 and 75. 1,2,3,h-Tetramethyl-5,6-dibromoben-

mm mm mm mm
zene (2%), which was easily available from the bromina-
tion of tetramethylbenzene in good yield and large
145

quantity, was used as the benzyne precursor. The

benzyne was generated at -78°C under argon by treating

146

TABLE 2

WIT H CYCLOPENTADIEN ES

THE CYCLOADDITION OFA BlS-ARYNE EQUIVALENT

 

 

Diene Solvent Bis-adduct Yield (Z)

ETHER O).[0 97
59
I

m THF 70
68

Ph P
l /

m THF 36
69
V

m TOLUENE 68
7O

TOLUENE 58

7]

 

 

 

 

“7

one equivalent of 2% with one equivalent of n-butyllithium.

Interception of this benzyne with dienes gg-Zl gave the
’b

adducts 81-85 in good yields (see Table 3). Physical

’Vb ’b’b

data for these adducts are quite similar to those of the
unsubstituted ones and also to their corresponding bis-
adducts. Although the lithium halogen exchange reaction
of n-butyllithium and o-dihalogenobenzenes has previously
been used in generating arynes,“6 the reaction conditions
that were worked out here in the synthesis of these
mono-adducts represents a considerable yield improvement
over the methods which were previously described for
adducts 68, 12, 13 and 12.

In conclusion, the bis-adducts which were described
in this part of the thesis are novel compounds. Their

syntheses are simple, afford the products in good yields,

and will enable one to explore their chemistry.

THE CYCLOADDIT ION O F

148

TABLE 3
TETRAMETHYLBENZYN E

WITH CYCLOPENTADIENES

 

 

Diene Solvent Adducr Yield (%l
O #6315 ‘"
S9 81
l
THF
a 5,
68 82
Ph Ph
Ph Ph |
63 U 5 ‘2
69 83
V
V
m TOLUENE U i 52
7O
TOLUENE 73

7I

 

 

 

 

149
3. Use of Bis-Aryne Equivalents in the Synthesis of

Iptycenes.
117

 

Bartlett was the first to synthesize triptycene
(£3), for the purpose of testing certain concepts in
physical—organic chemistry. For example, bridgehead-

substituted triptycenes were used to generate the

 

l3

corresponding carbonium ions, radicals and carbanions and
these were compared with their trityl analogs.L48 Interest
in triptycene rose sharply when it was shown by Wittig
that it could be synthesized easily in one step from
benzyne and anthracene,lu and at one point the formation
of triptycene actually became a test for the efficacy

of various benzyne precursors.u9 Eventually, the

synthesis of triptycene became a standard undergraduate
50

laboratory "experiment".
Many substituted triptycenes are known, and the

benzene rings have also been replaced with a variety of

51

other aromatic rings. The rigid framework is attractive

and has been used to study such diverse phenomena as

52

intramolecular charge transfer and restricted rotation

53

about single bonds. In the many structural variations

50

on triptycene, the triptych or tri—planar nature of the
structures has been preserved.5u

If triptycene is viewed ngt as a benzyne derivative
of anthracene but rather as a benzene which is ortho—
disubstituted by attachment to the 9,10 positions of
anthracene, then one quickly observes that this concept

might be extended by connection of two or three anthra-

cenes as shown in 86-88. We propose that these substances
NW NW

be given the trivial name of 'iptycenes'.

 

51

The name 'iptycene' emphasizes the relationship
between these compounds and the parent structure tripty-
cene. A prefix indicates the number of separated arene
planes; thus 13 is triptycene (3 planes), £6 and 21 are
pentiptycenes (5 planes) and $2 is a heptiptycene (7
planes). We believe that only three descriptors need
be added to these names to precisely define the structures.
The use of two of these descriptors is illustrated in

b.1.l]penti-

the following names: for 26 (R = H), [1.1.1
ptycene; for 21 (R = H), [1.1.la.l.l]pentiptycene; for
éé’ [1.1.1a’c.l.l.l.l]heptiptycene. The l's indicate
that each ring is benzenoid, and the appropriate number
would be replaced by 2 if naphthalenoid or 3 if anthra-
cenoid or phenanthrenoid, etc. The superscripts refer
to the bond (a, b or c) to which the sp3 carbons are
attached. We further suggest that these trivial names
be abbreviated for prototype compounds. Thus we will use

the names para- and ortho-pentiptycene for $6 and 21

respectively.

 

[ 2". I .1] "iPIYCN" [I .l.2 (b )b.| ,1] pentiptycene

52

A third descriptor, to indicate points of ring
fusion, may also be necessary; it consists again of a
bond (a, b or c) and is placed in parentheses. The
examples on the preceeding page illustrate the system.
These trivial names are, we believe, simpler to use than
the systematic CAS names, which are for 86 (R = H):
5,7,12,1U—tetrahydro-5,1U[1',2']:7,l2[l",2"]dibenzeno-
pentacene: for 87 (R = H): U,8,l3,lu-tetrahydro-
5,1U[l',2']28,13Fl",2"]dibenzenopentaphene; and for 88:
5,6,11,12,l7,l8-hexahydro-5,18[l',2']: 6,ll[l",2"]:
l2,l7[lm ,2m ]tribenzenotrinaphthylene.

Some compounds of this type already appear in the

56

literature. Thus 86 (R = H) was prepared by the

WW
addition of 2,3—triptycyne to anthracene. The yield
was 10%, and the required fluorobromotriptycene had to

be synthesized_from triptycene (in four steps, via nitro-,

Mg,THF

I 4 86 ( R =H )
a O F Anthracene

Br

 

amino- and 2-bromo-3-aminotriptycenes), so that the overall
yield from readily accessible starting materials was

quite low. Compound 86 (R = tabutyl) was synthesized

53

in low yield (3.7% crude, 2% purified) via bis-aryne

equivalent 82 by treatment with strong base.57 Although

not fully aromatic, the pentiptycene quinone 90 properly
mm

belongs among these compounds. It was originally reported

Br l-BUO- K.
O ’ “(Rn-bury”

Anthracene

 

Br

89

fifty years ago58 and can be considered as a substance
readily available in high yield from inexpensive precur—

sors, benzoquinone and anthracene.

 

As far as we are aware, no ortho-iptycenes such as
structure 81 have been previouly described.
Compound 88 was obtained in low, unspecified yield

as a minor product from the reaction of ll-chloro-9,10-

5U

 

dihydro-9,lO-ethenoanthracene (21) with butyllithium.59
CI H
/‘
g-Buli
O 4- ..
TIIF
9]

The structure assignment was based on spectra and the
space group of its crystalline lzl chlorobenzene complex.
Compound 88 is reported to have the remarkable melting
point, without decomposition, of 580°C.

Extension of our bis-annelation technology to
cycloadditions with anthracenes has led to a short general
synthesis of pentiptycenes 86 and 87 which will be described
here. The synthesis of 88 has also been re-examined and
improved, and the cycloalkyne intermediate derived from

2% has been trapped with several dienes.

A. Pentiptycenes with General Structure 86.

A toluene solution of anthracene and tetrabromo—p-
xylene (22), when treated with n-butyllithium in hexane
at -lO°C gave pentiptycene 86 (R = CH3) in 35% yield
(based on consumed anthracene). The product melts at
A60-U62° without decomposition.

The structure of 86 (R = CH3) is based on its

spectroscopic properties. The mass spectrum showed a

55

It} :.:.:::::-— ..

25

 

parent peak at m/g 458 and major fragmentation peaks at
uu3 (M+ - CH3), A27 (M+ - 2CH3), 280 (M+ - anthracene)

and 178 (anthracene)+. The 13C NMR spectrum of this
36-carbon compound showed only 7 peaks, consistent with
its D2h symmetry. The methyl carbons appeared at 6 lu.36,
the bridgehead carbon at 6 50.8“ and the remaining five
peaks were in the aromatic region. The proton NMR spectrum
of 86 (R = CH3) consisted of a singlet at 6 2.65 (6 H) for
the methyls, a singlet at 6 5.59 (A H) for bridgehead
hydrogens, and aromatic multiplets at 6 6.90 (8 H) and
7.28 (8 H). These data are quite similar to those of

the parent pentiptycene 86 (R = H) which was prepared by
Dr. Y. Takehira in our group. A similar procedure, but
with 1,2,U,5-tetrabromobenzene as the bis-aryne equivalent

precursor, gave an excellent yield of 86 (R = H) (9A%

based on consumed anthracene).

56

Other substituted pentiptycenes were also synthesized.

For example 86 (R = OCH3) was prepared in 36% yield and
one step from the reaction of tetrabromohydroquinone
dimethyl ether (22) with anthracene and n-butyllithium;
some reduced mono-adduct 23 was also formed. Compound

86 (R = OCH3) melts at N00-A02°C without decomposition.

The proton NMR spectrum shows peaks at 5 3.76 (s, 6 H,
OCH3), 5.50 (s, u H, bridgehead hydrogens), and aromatic
multiplets at 6 6.73 (8 H) and 7.10 (8 H). The 13C NMR
spectrum showed only 7-peaks. A single crystal X-ray

structure on 86 (R = OCH3) also confirmed the structure.
'V'b

 

 

(3CH3
3' Br n-Buli
O Anthra m? 86 ( R = OCH” .
8 Br (86%)
ocw,

92 93

57

Figure 2 shows the stereo drawing of this compound.

Appendix 2 gives the tables of bond distances and bond

angles.

Figure 2

 

Cleavage of the dimethyl ether 86 (R = OCH3) with
hydrogen iodide and acetic acid gave 86 (R = OH) in 97%
yield, mp A27-u30°c (dec). Oxidation of 22 (R = OH) with
ceric ammonium nitrate gave the known quinone 90 in

86% yield.

58

HI I CH,co,H
4"

 

86(R =OCH,)
Reflux

 

A pentiptycene with a central naphthalene ring
was obtained in good yield from tetrabromo-tetramethyl-
naphthalene (25).60 The structure of 95, mp 358-360°C,
mm

follows from its method of synthesis and spectra.

59

Br

3' n-BUU
i
8 Br Anthracene

94

 

 

B. Pentiptycenes with General Structure 87.
As far as we are aware, no examples of compounds

with this general structure were previously known. The
technique of ortho-bis-annelation, however, has been
used previously.61

The bis-aryne equivalent selected was u,5-dibromo-
3,6—diiodo-o-xylene (27), which was synthesized in two
steps and high yield from the corresponding dibromo
compound 96. This ortho bis-aryne precursor was selected

in order that initial lithiation, which is faster at

iodine than at bromine, be directed in such a way as to

 

I
Br
I .HgO,TFA 3'
O 1.. 0
Br 2 . l2 ’ Kl Br
I

96 97

60

produce the desired product. If the tetrabromo analog
of 91 is used, initial lithiation and lithium bromide

elimination can occur in an undesired manner.

Treatment of 91 with anthracene and butyllithium
gave 87 (R = CH ) in 19% yield, mp 382-384°C. The C
mm 3 2v
symmetry of 81 (R = CH3) requires only twelve different

'kinds' of carbons, and this is precisely what

 

n-BuLi . 87 (R = CH )
’VL 3

21 + anthracene toluene -23°C ’7

130 spectrum. There is one methyl signal

was seen in the
(6 15.32) but there are two bridgehead carbon signals
(6 50.18, 50.93) and appropriate aromatic peaks. The
mass spectrum of 81 (R = CH3) showed an intense M+ peak
(m/g U58, intensity 97), a base peak at m/g 280 (M+-

anthracene) and a fairly intense peak at m/g 178

(anthracene, intensity 52).

C. Heptiptycene 88 and Cygloalkyne 10b.
fiu’b 'u’b'b
Huebner, et al. showed59 that at -78°C in THF 91
was metalated by n-butyllithium to give the a-lithio
derivative 98 which on carbonation gave the chloro
acid 22. We verified this result using t-butyllithium
at —h2°C. Quenching of 98 with CH OD or CH I or BrCH -
mm 3 3 2
CH2Br gave 122, 101 and 122 respectively. Thus 98

’V‘b
is relatively stable toward elimination of lithium chloride.

61

 

CI /li Cl R
g-Buu 3 E
9‘ mg: a O —'* 3 O
98
99 (R=C02H)
100(R: D)
101 (R: 04,)
‘02 (R : Br)

When a solution of 28 (prepared at -N2°C using t-butyl-
lithium) was warmed quickly to room temperature and then
heated under reflux for 2 h a 20% yield of the hepti-
ptycene 88 and a 39% yield of coupling product 103

mm mmm
was obtained. This procedure represents some yield

improvement over the literature.59

 

98 R:::x 33(20%) + O 5 I“
C. {fills}

103 (39%)

62

The presumed intermediate in the formation of 88 is
mm

the cycloalkyne lgh. To trap this intermediate, solutions
’b

of 98 were prepared at —fl2°C and added dropwise to
NW

 

THF

€H3---—>-
reflux

    

 

104

‘5' 106

 

 

 

(42 %) 107

63

refluxing THF containing various dienes. In this way,
adducts 105-107 were prepared in reasonable yields.
mmm mmm
Reaction of organolithium reagents with cyclic
vinyl halides has been discussed as a route to strained
cycloalkynes.62 For example, recently Gassman and

63 reported generation of bicyclo[2.2.l]hepta—

coworkers
2—yne and its trimer. But cycloalkyne $23 appears not
to have been trapped previously and synthetic utility of
this easily accessible reactive intermediate and the
formation of related derivatives could be explored.
In the experimental section we describe an improved
synthesis of its precursor 9%.

In conclusion, a short, reasonably efficient synthe-
sis of pentiptycenes with the general structures 82 and
81, a synthesis which will permit exploration of the
chemistry of these novel compounds and their derivatives,
has been developed. The yield of heptiptycene 88 has been
improved by using t-butyllithium in place of n-butyllithium
in the metalation of 9% and the presumed intermediate in
its formation, cycloalkyne $23, has been trapped with
various dienophiles. The chemistry of triptycene analogs

such as 86-88 can now be explored.
’b’b 'VX:

6“

u. Application of Bis-Aryne Equivalents to the Synthe—

sis of Phenanthrenes.

 

Phenanthrene was first discovered in coal-tar in

1872.6“

Today, coal-tar is still the most important raw

material for its preparation. However, there are numerous

syntheses of phenanthrene and its derivatives. In this

section, synthesis of_methyl derivatives, and especially

hindered phenanthrenes, will be emphasized, as well as

our new and simple synthesis of phenanthrenes.“a
Phenanthrene synthesis from succinic anhydride,

naphthalene and aluminum chloride is particularly impor-

tant for the preparation of homologues.65 Scheme 6 shows

Scheme 6

 

 

 

this general procedure. The keto—acid 108 is reduced by
mmm

the Clemmensen method,the ring is closed, the product is

65

then reduced as before and dehydrogenated. A variety
of reagents have been used by different authors in these

65 In 1965, A. Cornu and J. Ulrich66 used this

steps.
already well-known method to synthesize 18 alkyl phenan—
threnes.

Considerable interest is associated with “,5-
dimethylphenanthrene (llg) because of the steric hindrance
associated with such a structure. These U,5-positions

67 Newman,68 in 19uo,

"impossible" positions.

were called
predicted that molecules containing the u,5-dimethylphen-
anthrene system might be capable of optical resolution
due to interference between the methyl groups in the
hindered positions. Three possible geometries were
suggested for this system: (1) the methyl groups may
bend away from each other but still lie in the same
plane as the aromatic rings; (2) the aromatic rings may
be distorted in some way; (3) the methyl groups may be
bent out of the plane of the aromatic rings. If the first
alternative were correct, there would be no asymmetry
and the molecule would not be resolvable. However if
the second or third alternative, or combination of these
two, were correct the molecule would be capable of
resolution.

Newman showed that alternative 2 or 3 is correct
by the successful resolution of U,5,8-trimethyl-l-

phenanthrylacetic acid (109).69
mmm

66

O O 121..

CH,
1(T9

X-ray crystallographic investigation of the struc-
tures of overcrowded aromatic compounds by Schmidt and

70

coworkers showed that the asymmetry introduced into a

molecule by intramolecular overcrowding is caused by

a combination of the two alternatives previously mentioned;

that is, by a folding of the benzene rings, and, if there

are groups present in the hindered positions, by the

assumption of non—coplanar positions for these groups.
Unsuccessful attempts to synthesize N,5-dimethyl-

71

phenanthrene were reported by several authors. In

67

19u9, Newman and coworkers were successful and reported

the first synthesis of “,5-dimethylphenanthrene (llé)
(Scheme 7). Ozonization of pyrene (112) gave the
aldehydo-acid 111, which was converted to its ethyl
ester 1&2. Subsequent reduction of 112 with lithium

mmm
aluminum hydride gave thediol 113 which was converted
'V'b’b
to cyclic ether 11“ by acid. Reduction of llh with
’VVM ’VVV
hydroiodic acid and red phosphorus under very careful condi-

tions gave 112. The last step afforded only 17% of 115.
NW N’b'b

67

 

Scheme 7:
’CH 03 /Cl:OH C: “so“ ICrow,
R\" ——P~ R\ ’0 + )-
CH co H \C6
"0 "I "2

C LiAIH,

 

 

/CH3 HI /CQ2 HC' /CH20H
R\ 4‘—-—- R\ / «t R\
CH, P CH, CH,0H
"5 H4 "3

72

A few months later Badger and Campbell independent-

ly reported a synthesis for 112. Their strategy was
somewhat similar to that of Newman. After preparation
of the diol 113 by a similar procedure, it was converted

’VVM
to its corresponding dibromide 116. Direct reduction of
mm ,
116 was unsuccessful. Therefore 116 was converted to its
'b’Vb 'Vb'b
diisothiuronium dibromide which underwent smooth hydrogeno-

lysis with Raney nickel to give 112 in 76% yield.

68

/CH,Br ‘) "Hf-g —NH’

 

[cazon PB,
a\ -—3—> k 5—-> us
04on CHaBr 2) Ni—H,
"3 "6

73

Wittig and Zimmerman, in 1953, used a completely

different method to synthesize 115 (Scheme 8).
’V'U'b

Scheme 8

 

69

In this synthesis anthranilic acid 111 was prepared

from corresponding isatin. The diazonium carboxylic

acid derived from 111 was coupled in the presence of
cupric sulfate to give 118. Reduction of 118 with lithium

'Vb'b
aluminum hydride gave diol 119a which upon treatment with

phosphorus tribromide gave dibromide 1192. Cyclization
of 1192 was achieved in good yield using phenyllithium,
to give 128. The final dehydrogenation was carried out
in a steel bomb at BOO-305°C in the presence of 5%
rhodium on alumina. The total yield of 115 starting
from anthranilic acid 111 was about 25%. This method

7“ for the synthesis of

was adopted by Newman in 1965,
3,“,5,6- and 2,H,5,7-tetramethylphenanthrenes.

Newman's interest in the synthesis of compounds
containing methyl groups in close proximity to each other
developed from the problem of their chemical carcino—
genity. He determined the strain energies in these
hydrocarbons from their heats of combustion.75 His data

showed that “,5-dimethylphenanthrene is more strained

than the 2,7-dimethy1 isomer 121 by 12.6 i 1.5 kcal/mol

NM
and 122 is more strained than 123 by 7.2 i 1.“ kcal/mol,
mmm mmm 6
due mainly to the buttressing effect.7
Recently,77 Newman reported a synthesis for 9-bromo

derivatives of 122 and 123, in order to compare rates
'b’b’b 'VVM .
of reaction by an electrophilic substitution mechanism

in strained and unstrained polycyclic aromatic

7O

hydrocarbons.78

In this work he reported an improved
method for cyclization of 12“. Treatment of 12” with
’Vb’b 'VVb
sodium amide in liquid ammonia directly gave the desired
phenanthrene 125. The cyclization occurred only when a
mmm

stainless-steel stirrer was used. When a nylon-coated
magnetic stirrer was used, the starting dichlorides were

recovered and the nylon stirrer was black.

    
 

CH,C[ NaNH,

 

 

CH2CI N“:

 

124 I25 126

Addition of bromine to the 9,10—bond of 125 yielded a
mmm

9,10-dibromo-9,10-dihydrophenanthrene. Subsequent elimi-

nation of hydrogen bromide yielded the desired phenan—

threnes 126.
WWW

71

Success in using the o-bis-annelation technique to
synthesize o-pentiptycene 81 led us to explore a new
and simple phenanthrene synthesis. As described in the
synthesis of 87, dibromodiiodo-o-xylene 91 functions as
an o-bis-aryne equivalent upon treatment with n-butyl-
lithium. When a solution of 91 (1 equivalent) and furan
(excess) in dry toluene at -78°C under argon was reacted
with 2 equivalents of n-butyllithium a 71% yield of bis-

adduct 127 was obtained as a mixture of syn and anti

N’b’b
n-Buli <:)
>
toluene, “78°C *

isomers.

 

 

u 127
97 tH [Pd/C
. O
E<3H
O O “"17-
129 123

The 1H NMR spectrum (CD013) of this mixture does not show
separate peaks for the two isomers; rather, the peaks

are either overlapped or slightly broadened. A sharp

72

singlet at 6 2.13 (6 H, methyls), a broad singlet at

6 5.60 (A H, bridgehead hydrogen), and a broad singlet
at 6 6.80 (U H, vinyl hydrogens) were observed. Further
identification of 127 was achieved by its conversion to

79

the known 9,lC-dimethylphenanthrene 129. To remove

the oxygen bridges, a solution of lgzmwas hydrogenated
over palladium on charcoal. Treatment of the reduced
product 128 with a saturated solution of HCl in ethanol
gave 129 in greater than 90% yield, mp 1U0°C (lit.79
1&0.5°C).

Using 2,5—dimethylfuran in a similar reaction gave
a 34% yield of bis-adduct 130 as a mixture of syn and
anti isomers. This mixturemwas separated by column
chromatography on alumina. The major isomer, which was
eluted first, had a proton NMR spectrum consisting
entirely of singlets, at 6 1.86 (6 H), 1.90 (6 H),
2.13 (6 H), and 6.50 (s, u H), whereas the spectrum of
the minor isomer showed a doublet of doublets for the
vinyl hydrogens and three other singlets with approxi-
mately the same chemical shifts as for the major isomer.
The 13C NMR spectrum of each isomer consisted of 10
signals for this C2O-compound, which shows the presence
of a plane or C2 axis of symmetry. For the major isomer
the signals are at 6 1n.3o, 19.15, and 20.27 (methyls),
88.51, 89.31 (bridgehead carbons), and five peaks in

the aromatic region.

73

O H O
fi-‘fiifi’fin

130 131

HV
0% fi

132 I33

 

When a procedure similar to that used for 127 was
mmm

used to remove the oxygen bridges from 130, a 1:3 mixture
of hexamethylphenanthrene (132) and the rearranged hydro-
carbon 133 was obtained. The physical properties of

132 will be described later in this section. The mass
spectrum of 133 showed that it is an isomer of 132. The
structure of this isomer was determined from its proton
NMR spectrum: 6 0.88 (d, i = 8 Hz, 3 H), the aliphatic
methyl; 2.23 (s, 6 H), 2.33 (S, 3 H),2.M0 (s, 3 H), the
aromatic methyls, 3.U3 (q, i = 8, 2 Hz, 1 H) the hydrogen
next to the aliphatic methyl, N.93 (d, g = 2 Hz, 1 H)

and 5.20 (d, g = 2 Hz, 1 H), the vinyl hydrogens; 6.86

(s, 2 H) and 7.00 (s, 2 H), the aromatic hydrogens.

7”

In order to find out whether 133 is a primary
'b
product of the reaction of 131 with acid or whether it
is formed as a secondary product from further reaction of
hexamethylphenanthrene 132 with acid, a solution of 132
’Vb’b ’Vb'b
was treated with ethanol saturated with HCl, under
exactly the same conditions as for 131. After work-up
'Vb’b
the reaction mixture contained 76% of 133 and 2N% of
unreacted 132. Thus 133 is a secondary reaction product.
’VV'b ’b’b’b
The unsatisfactory removal of the oxygen bridges
from 130, which gave mainly the undesired rearranged
product 133, led us to look for a different diene, the

Wmm
bis-annelation product of which could be aromatized in
good yield without rearrangement. Dimethylaminopyrroles
were previously used in our laboratory in the synthesis

20’80 Aromatization of the

of some polymethylarenes.
bis-adducts derived from these pyrroles was achieved either
by m—chloroperbenzoic acid oxidation or by pyrolysis.
The nitrogen bridges were eliminated to give the corres-
ponding polyarenes in excellent yields. This method was
discovered by Schultz.81
82 80
Pyrroles 133 and 135 were prepared in good
yields by azeotropic distillation of the corresponding
2,5-hexanediones and 1,1-dimethylhydrazine. Bis-annelation
of pyrrole 13A and arene 87 gave a “6% yield of bis-
mmm mm
adduct 136 as a mixture of syn and anti isomers. The

major isomer was purified by trituration of the crude

product with hexane. The proton NMR spectrum

75

of this isomer consisted of singlets at 6 1.80 (6 H)

 

 

Br
n'Buli
O + A Toluene, 78°C» 0
Br ”I
I N
/ \ R=N(CH:)2
87 I34 I36
I
°' 0
n-Buli
O + I \ Toluene,'78°C) Q m
Br '“
l
l / \
R=N(CH,),
87 I35 I37

and 1.83 (6 H), 1,U,5,8-methyls; singlet at 5 2.16 (6 H),
9,10-methyls; a broad singlet at 6 2.28 (12 H), N-methyls,
and a broad singlet at 6 6.M3 (h H), vinyl hydrogens.

The 13C NMR spectrum of this isomer showed peaks at

6 14.93 (9,10-methyl), 18.72, 19.u3 (l,M,5,8-methyls),
45.69 (N—methyls) 7h.7l, 76.15 (bridgehead carbons)

and 126.uu, 1u5.75 1h6.oo, 1H6.52, 1h6.75 (Sp2 carbons).

The electron impact mass spectrum of 136 did not show a

76

parent peak but had a base peak at m/g 262 corresponding
to [M+ - 2N(CH3)2]; however, the chemical ionization
mass spectrum gave an (M + l)+ peak at m/g 379.

Bis-adduct 131 was also prepared by a procedure
similar to that used for 127, from the bis-annelation of
pyrrole 132 and arene 81. The yield of the mixture of
syn and anti isomers of 131 was HU%. The proton NMR
spectrum of the major isomer showed singlets at 6 1.56
(6 H), 1.60 (6 H), 1.76 (6 H), 1.80 (6 H), 2.16 (6 H),
2.U3 (12 H); the 13C NMR (spectrum) was similar to that
of 136 and consisted of peaks at 6 10.50, 11.38, (2,3,-
6,7-methyls), lu.77 (9,10-methyls), 17.63, 18.69 (1,h,-
5,8—methyls), u5.83 (N-methyls), 76.12, 76.30 (bridgehead
carbons), and four other peaks in the aromatic region.
The electron impact mass spectrum did not show a parent
peak, but a base peak at m/g 318 correspondingto
[M+ - 2N(CH3)2]. However, the chemical ionization mass
spectrum gave an (M + l)+ peak at m/g N35.

As previously pointed out, the mass spectra of
adducts 136 and 131 failed to show parent peaks; rather
they gave base peaks corresponding to the bridge-removed
products. This indicated that pyrolysis of 136 and 131
could very well lead to hexamethylphenanthrene (132)

or decamethylphenanthrene (138), respectively.

77

‘36 ISO‘C 4 O O O

0.1 torr, Ih

 

1132

‘37 l70-lBO’C 4 O O O

0.] Iorr; 2h

 

1138

When 136 (50 mg) was pyrolyzed at its melting
point (1H7-1N9°C) at 0.1 torr for 1 h it gave a 90% yield
of 1,9,5,8,9,10-hexamethylphenanthrene (132). The proton
NMR spectrum of 132 showed singlets at 6 2.9u9 (5 H),
2.631 (6 H), 2.817 (6 H), and an AB quartet for the
aromatic protons centered at 6 7.171. The 13C NMR
spectrum consisted of 10 peaks for this C20-carbon
compound, three peaks at 6 20.79, 22.02, 25.u7, for
the three types of methyl groups, and 7 peaks in the
aromatic region. The mass spectrum showed the parent
peak, which was also the base peak, at m/g 262. The

ultraviolet absorption spectrum of 132 in heptane showed

78

Amax at 329 nm (log a M.U3), 266 (M.90), 291 (4.6“).
Decamethylphenanthrene (138) was prepared similarly
in 87% yield by pyrolysis of 131 (100 mg) at around its
melting point (170-180°C) at 0.1 torr for 2 h. The
proton NMR spectrum of 138 in chloroform showed a broad
singlet at 6 2.33 (18 H)tmand singlets at 2.6M (6 H)
and 2.53 (6 H); the proton NMR spectrum at 180 M Hz in
C6D6 showed singlets at 6 2.227 (12 H), 2.536 (6 H),

2.368 (6 H), 2.u91 (6 H). The 13

C NMR spectrum showed
four peaks at 6 16.57, 20.88, 21.08, 21.96 (two of the
methyl carbons are overlapped), and six peaks in the
aromatic region (two of the sp2 carbons are also
overlapped). The mass spectrum showed a parent peak
which was also the base peak at m/g 318. The ultra-
violet spectrum in heptane showed Amax at 325 nm
(log a H.1u) and 277 (9.73).

In conclusion, a simple and general synthesis of
phenanthrenes has been developed which is especially
applicable to the synthesis of hindered derivatives.

The yields are good and comparable to the previously

described methods, with fewer steps.

79

5. Polyphenylarenes: ChmnunsSandwiched Between Phenyl

26.926-

In the past 20 years, many anthracene and naphtha-
lene derivatives which contain at least two aryl substi—
tuents at peri positions have been synthesized in order
to study their chemical and physical properties. 0f the
many methods which have appeared in the literature, only
a few examples will be mentioned.

l,U,5,8-Tetrapheny1naphthalene83 (131) was synthe—
sized by reaction of 13% with phenyllithium to give

the two stereoisomcrs of 1140. Dehydration of 1110 with
N’b’b 'L’V'b

HCl/CH3COOH gave 1H1.
’VVL

 

(M1 Ph
Phli
CflaCCNDH
Ph 0 OH ”I
1 39 ‘4]

A similar procedure was used to synthesize l,“,5,8,9,10-
hexaphenylanthraceneBu (15%) (Scheme 9).

Cycloaddition of benzyne and 3,6-diphenylisobenzofuran
was used by Wittig13 to synthesize 9,10—diphenylanthracene
85

(12), as previously mentioned (p. 8). Stevens later

used the same strategy to synthesize 1,2,3,u,9,1o-
hexaphenylanthracene, by cycloaddition of benzyne to

hexaphenylisobenzofuran.

80
Scheme 9

K + .;?flz_.>
\

Ph h o n. Pk 0
Ph h 0 Ph Ph 0

 

Kl lcu,coou
h Ph Ph 0
h

P
P
P Ph Ph
W « ”22's; 0 O
P Ph Ph

142

House and coworkers86 have tried several different
procedures to synthesize phenyl substituted anthracenes
and naphthalenes, in order to study the restricted rotation
of the phenyls at the peri positions. 1,8—Dipheny1naph-
thalene was synthesized by the coupling reaction of

1,8-diiodonaphthaleneanuiPh CuLi. Also, 1,2-addition of

87

2
phenyllithium to quinones was used in a number of cases.

Pentacene and its derivatives have also been used
in various studies such as determination of resonance

energies of polyacenes,88 the rate of the reactivity of

81

benzenoid hydrocarbons89 (i.e., in Diels-Alder reactions),
and semi-empirical SCF-pi-molecular orbital studies.9O
Many of the substituted pentacenes have been prepared
from pentacene itself. 6,13—Dipheny1pentacene and
5,7,12,1b-tetrapheny1pentacene were prepared by the
action of either a Grignard reagent or phenyllithium on
6,13-pentacenequinone (133) and 5,7,12,19-pentacenedi—

quinone (lbu), respectively.91
’b'b'b

 

6,13-Di1ithiopentacene (152) was obtained by the action

92

of Li on pentacene. The 6,13-dialkyl dihydro

derivatives 1&6 were obtained from action of the dilithium
’b’b’b

compound 135 with alkyl chlorides.93

 

coco 1 «was

145 I46

82

Pentacenes are very reactive and, in solution,
absorb atmospheric oxygen (very rapidly in sunlight)
91

to give a peroxide. The photooxidation rate decreases
from pentacene > naphthacene > anthracene.9l

It was thought that the bis-annelation reaction
could furnish a simple route to these polyphenylarenes,
provided an efficient method could be found to remove
the bridges from the corresponding bis-adducts. 2,5-
Diphenylfuran (197) or 3,6-dipheny1isobenzofuran (1M8)

'Vb’b 'Vb'b
were selected for cycloadditions with bis—aryne equiva-
lents to further demonstrate the capability of this
bis-annelation reaction.

A toluene solution of 3,6—diphenylisobenzofuran
(198) and tetrabromo—p-xylene (25), when treated with
'Vb’b ’V‘b
n-butyllithium in hexane at -78°C gave 67% of bis-adduct
1M9 (R = CH3) as a mixture of two geometric isomers.

’b’b’h

The structure of 1M9 (H = CH3) is based on spectroscopic
mmm

properties which were obtained for the major isomer. The
mass spectrum showed a parent peak at m/g 692. The 13C
NMR spectrum of this OMB-carbon compound showed only 13
peaks, at 6 17.u3 (methyl), 91.67 (bridgehead), and the
expected aromatic peaks. The proton NMR spectrum of

139 (R = CH3) showed a singlet at 6 1.93 (6 H) which is
shifted upfield 0.8 ppm compared to the 2,5-dimethy1furan

adduct 29. This upfield shift is because of the ring

83

current of the benzene rings. The aromatic hydrogens
appeared as a multiplet at 6 7.30—7.85 (28 H).

Bis-adduct 132 (R = 0CH3) was also prepared in one
step and “2% yield from the reaction of tetrabromohydro-
quinone dimethyl ether (92) and diphenylisobenzofuran,
as a mixture of anti and syn isomers. The mass spectrum
with chemical ionization showed (M+ + l) = 676. The
130 NMR spectrum showed only 13 peaks for this CAB-carbon
compound. In the proton NMR spectrum the methoxyl
signal appeared at 6 2.66, which is shifted appreciably

upfield compared to an ordinary methoxyl group.

 

R Ph ll Ph
Ph
Br Br
+ ,0 ".1, @066 o

Br Br \ Toluene, 78°C

R Ph Ph R Ph
25 R=CH3 =CH,

49

92 R=OCH3 ‘48 I R=OCH3

Reaction of tetrabromo-p-xylene (22) with 2,5—
diphenylfuran (197) and n—butyllithium at 0°C gave 150
mmm mmm
(R = CH3) in 52% yield (based on diphenylfuran used).

The product was identified by its spectroscopic data.

8U

 

R Ph R Ph
Br Br 8 l'
n- u: .
+ A Toluene, 78°C m Q @
Br Br ”I 0 Ph
R Ph R Ph
R=CH3 l47 R=Clnla ISO

When arene 92 was used with 2,5-diphenylfuran some
'b’b

reduced mono-adduct 121 was also formed.

n-Buli

92 + 147
Toluene

> 150 (R=OCH3) +

 

The hexacene derivative 152 was prepared in 82%
mmm

yield from the reaction of tetrabromo—tetramethylnaphtha-

lene (9D) with 198 and n-butyllithium, and was obtained
mm

 

’Vb’b
as a mixture of two isomers. The structure of 152
'Vb'b
Br
n-Buli ,_ 3
+129
Br Br

94 152

85

follows from its method of synthesis and spectra.

Known literature procedures were applied to the
aromatization of these bis-adducts, in order to obtain
the corresponding pentacene or anthracene derivatives.
However, when $32 (R = CH3) was refluxed in acetic acid
with zinc dust for 2 h, reaction did not proceed to give
pentacene 153; rather, it gave the quinonedimethide 15“

in quantitative yield.

 

 

 

 

 

I! ,
I]
3
149 (R=CH,) c2663: ‘5
Reflux
Ph Ph
» 33033
Ph Ph
‘54

Compound 15“ was characterized by its spectroscopic data.
’V‘Vb

The 1H NMR spectrum showed a broad singlet at 6 “.86 (“ H)

fer’the vinyl protons and a multiplet at 6 7.0-7.“0(28 H).

The mass spectrum showed the parent peak at 131/; 608.

86

In another attempt to remove the oxygen bridges,
$32 (R = CH3) was treated with n-butyllithium in the

9“ No reaction

presence of anhydrous ferric chloride.
occurred and the starting material was recovered.
Bis-adduct 132 (R = 0CH3) was also treated with zinc
dust in acetic acid in the dark and under argon. The
reaction mixture became blue after 15 minutes of reflux,
and the color continued to darken, up to 1 h. The forma—
tion of a blue solution is very strong evidence for the
formation of a pentacene. The reaction was stopped
after 2 h at reflux, and the mixture was cooled to room
temperature. Deoxygenated water was added and the
solution was filtered under an argon atmosphere in
darkness. A greenish-blue solid remained. A proton
NMR spectrum of this crude product showed a singlet at
6 3.61 (6 H) and a multiplet at 6.90-7.30. The mass

spectrum showed a parent peak at m/g 6“2, corresponding

to the expected pentacene 155.
WWW

Ph (DNke Ph

l49lR=OCH3) E: 235:)?- O O
3
Reflux

Ph (DNk: Ph

 

155

87

Attempts to purify this compound were not successful
because the blue product changed to a colorless compound
which showed several spots when subjected to TLC. Perhaps
more careful conditions (total absence of oxygen and
light) are required to purify pentacene 125.

In conclusion, the bis-annelation technique is capa-
ble of being used to synthesize polynuclear aromatic
compounds provided an efficient procedure is available
to remove the oxygen bridges. At this point more study
is required in order to find a method to efficiently

aromatize bis-adducts of this type.

88

6. Attempted Synthesis of N-N Bridged Bis-Adducts of

 

Bis-Aryne Equivalents: Basket-Type Compounds.

 

The synthesis of bridged aromatic compounds has long
95

been a challenge for organic chemists. There are
several general reasons for studying bridged aromatics.
Perhaps the most interesting question arises from the
geometry of the compounds. Generally, these species
have a definite fixed geometry with limited or restric-
ted rotation around the covalent single bonds, and

such rigidity and deformation in some cases give unusual
properties to the compounds.

In further attempts to extend the utility of the
bis-annelation technique, the synthesis of some bridged
aromatics such as 156 was attempted. Since bis-aryne
equivalents have two reaction sites it is plausible
to expect an inter—intra-molecular Diels-Alder adduct,
if a molecule with two diene functionalities is used.
Thus, dipyrroles of the type 155, which are readily
prepared in excellent yield from diamines and l,“-

96

diketones, were considered.

.6 av- "‘
B

[55
n: 3 ,4,5

89

Two strategies were used in the attempted synthe—
sis of 126. The first approach was a simple one-step
synthesis, similar to the general procedure that was
used previously in bis-annelation reactions. Thus, a
suspension of tetrabromo—p-xylene (25) (10 mmol) and
dipyrrole 122 (n = 5) (10 mmol) in toluene at -78°C
under argon was reacted with n-butyllithium (20 mmol).

After work-up the reaction product contained polymeric

Br Br / \ _r_r_- Bu Li
Br 0 a: \ N—[CH’JS-N / f %
25

155

 

(CH2),\

/

 

156

materials, suggesting that the reaction proceeded by an
intermolecular process rather than intramolecularly. In
a similar reaction but using high dilution techniques,
there was no change in the composition of the reaction

96

products.

90

The other approach took advantage of the stepwise
nature of the bis—annelation reaction. Treatment of
mono-adduct 127 with n-butyllithium using the high
dilution technique might afford a good chance for
intramolecular cycloaddition, to form 156. Therefore,
in an attempt to synthesize mono-adduct :57, a suspension
of tetrabromo-p-xylene (22) and dipyrrole 122 (10 mmol
each) in toluene at -78°C under argon was reacted with
10 mmol of n—butyllithium. After work—up, the reaction
mixture contained notcnfinrlzl adduct 127, but some 2:1
adduct of tetrabromo-p-xylene and dipyrrole (128). The
ratio of the 1:1 adduct to the 2:1 adduct depended upon
the number of methylene groups in the starting dipyr-
roles.

The proton NMR spectrum of 127 (n = 5) shows a
multiplet at 6 1.03-1.66 (6 H, methylenes), singlets
at 6 1.76 (6 H), 2.16 (6 H), 2.“6 (6 H) for the three
sets of methyl groups, a multiplet at6 3.“3-3.83 (ll H,
methylenes next to nitrogens) and singlets at 6 5.65
(2 H, vinyl hydrogens of the pyrrole moiety) and 6.53
(2 H, vinyl hydrogens). The 13C NMR spectrum of this
CZS-carbon compound showed 15 peaks, as expected from
its symmetry, at 6 12.7“, 18.“1 and 20.60 (methyls),
25.29, 30.91, 31.58 (methylenes in the middle of the
chain), “3.“9, “5.30 (methylenes next to nitrogen),

77.39 (bridgehead carbon), 105.05 (C2 and C5 in the

91

125 + 155

n-Buu

 

/ N’ [CH2]n
— ) E...)
N / '\

Bl’ Br N N
I + Br
Br Br 0 l Bf
157; l=l adduct ISB ; 2 :1 adduct
51 X n : 3 2] X
15 X n :4 47%
24% n:5 4T1

pyrrole ring) and five expected sp2 carbons in the
aromatic region. The mass spectrum showed a parent
peak at m/g “30 and a base peak at m/g

16“ [(M” — (CH2)5—N:j ].

For 158 (n = 5) the proton NMR spectrum consisted
of peaks at 6 1.0-1.60 (m, 6 H, methylene hydrogens),
1.76-2.16 (m, “ H,methylenes next to nitrogens), 1.76
(s, 12 H, methyls on the bridgehead carbon), 2.“3 (s,
12 H, methyls on the benzene ring), and 6.50 (s, “ H,

vinyl hydrogens). The 130 NMR spectrum of this 0 -carbon

33

92

compound showed only 10 peaks, consistent with its

C symmetry; the methyl groups appeared at 6 18.“2

2v
and 20.62, methylenes at 6 26.09, 31.71 and “5.37,
the bridgehead carbon at 6 77.“0 and the remaining
four peaks in the aromatic region.

The structures of compounds 157 (n = 3,“) and
158 (n = 3,“) were determined by their spectroscopic
data. Table “ compares the 13C NMR spectra of 157
and 15% (n = 3,u,5) and Table 5 compares the 1H NMR
spectra of these adducts.

In an attempt to cyclize adduct 157 (n = 5), a
'VV'D

solution of 157 (n = 5) (1.5 mmol) in 100 mL of toluene

/ N’ [CH2],
, )
I!

Br n—BuU

/ t—jl—u> l56

 

Br
l57(n=5)

and n-butyllithium (3 mmol) in 100 mL of hexane were
added dropwise simultaneously to 250 mL of dry toluene
at -78°C under argon over a period of “ h. Attempts to
obtain a pure product from the reaction mixture failed.
Perhaps some butylated products along with polymeric

material were present.

93

TABLE 4

”C-NMR CHEMICAL SHIFTS (ppm) 071:1 ADDUCTS
l57(n=3,4,5) AND 2:1 ADDUCTS 153 (n=3, 4,5)

 

 

 

 

 

 

 

 

 

 

 

 

 

Compound Solvent Agizclat bald-9:1, N-CH, Me?ll:|eelne5 Methyls
150.3
147.4
132.9 20.6
157(n=31 CDCI, '27-] 77.4 42-5 32.5 18.4
126.3 44.0 12.5
126.2
a 105.1
150.3
147.6 20.5
1571n=41 CDCI, 132" 77.4 45‘2 30'3 18.5
127.2 43.5 29.0 12.6
126.3
105.1
150.4
147.5 31.6 20.6
lS7(n=5) CDCIa 12:33 77.4 2:: 30.9 13.4
“26.2 25.3 12.5
105.0
150.3
153111.13) CDCIa 12:: 77.4 43.9 33.06 12::
126.7
151.2
158(n=4) 0330‘“ ”7'3 77.3 44.9 29.6 20,5
CCI, 131.9 13.3
125.7
1505
147.6 31.7 20.6
158(n=5) CDCI, 132.3 77.4 45.4 26.] 13.4
126.1

9“

TABLE 5

‘H NMR CHEMICAL SHIFTS (ppm) or 1:1 ADDUCTS
l57(n= 3,4, 5) AND 2:1 ADDUCTS 153 (6:3,45)’

 

 

 

 

 

 

 

 

Vinyl Pyrrolel Other AromJB'idge' Pyrrole
d _
Compoun H H N CH; Methylenes CH3 lag: CH3
6.50 5.63 3.43-3.76 2.10-2.15 2.43 1.73 2.13
157 (n=3) . .
(s, 2H) (s, 2H) (m,4H) (m,2H) (s, 6H) (,,6H) (s, 6H)
6.50 5.56 3.36-3.66 1.30-1.66 2.40 1.76 2.13
157 (n=4) , 7
‘ (s, 2H) {5,2H) (m,4H) (m,4H) (5,6H) (s, 6H) (s, 6H)
6.53 5.65 3.43-3.33 1.03-1.66 2.46 1.76 2.16
157 (n=5) .
(s, 2H) «s, 2H; (m,4H) (m,6H) (5,6H) (s, 6H) (s, 6H)
6.50 1.73-2.40 2.40 173
158 :3 '
(n ) (5, 4H) lm,6H) (5,12H) (5,12H)
153 (n_4) 6.53 1.90-2.33 1.50-1.66 2.40 1.76
(s, 4H) (m,4H) (m, 4H) (5,12 H) (3,12 H)
158 (n-s) 6.50 1.76-216 1.00-1.60 2.43 1.76
' (5, 4H) (m, 4H) (m, 6H) (s,12 H) (s,12 H)

 

 

 

 

 

. Spectra run in CDCIa as solvent.

 

 

95

It seems likely that the geometry of the mono-
adduct 157 is such that it prefers to undergo intermo-
lecular cycloaddition, rather than intramolecular, to
form polymeric material. However, attempts by others
in this group to synthesize these basket-type compounds
are still in progress.

In conclusion, although it was not possible to
obtain any N-N-bridged basket-type compound, novel
adducts such as 157 and 158, were synthesized the

'b’b’b ’L’Lq,
chemistry of which could be explored.

96

EXPERIMENTAL

l. General_procedures

 

1H NMR spectra were measured at 60 MHz (Varian T-60),

or on a Bruker WM-250 or Bruker 180-MHz spectrometer'using
(CH3)uSi as an internal standard. Chemical shifts are

13C NMR spectra were measured on

reported in ppm (6).
a Varian OFT-20 spectrometer. IR spectra were determined

on a Perkin Elmer Model 167 spectrometer. UV spectra were
obtained on a Cary Model 219 spectrometer. Mass spectra
were measured at 70 eV using a Finnigan “000 spectrometer
with the INCOS data system, operated by Mr. Ernest Oliver.
High resolution mass spectra were obtained with a Varian

CH5 spectrometer. Melting points were determined with an
Electrothermal Melting Point Apparatus (Fisher Scientific).
To extend the range about 360°C, the apparatus was connec—
ted to one or two Variacs (in series) each of which could
nominally boostljxmzvoltage from 110 V to l“0 V and the
thermometer was replaced by an iron-constantan thermo-
couple. The thermometer well was blocked with a glass

rod to minimize heat loss, and the thermocouple was placed
in a melting point tube well adjacent to the well holdingtflue

sample tube. After the approximate mp range was determined,

the block was pre-haated to approximately 50° below the

97

expected mp before inserting the sample. Microanalyses

were performed by Spang Microanalytical Laboratory,

Eagle Harbor, MI.

2. Tetrabromo—p-xylene (25)
’D

 

To a suspension of l g of iron powder in 20 g (0.19
mol) of p-xylene at 0°C was added dropwise 96 mL _
(1.8 mol) of bromine. The reaction mixture was left
overnight, then the excess bromine was destroyed bynadding
saturated aqueous NaHSO3. The solid was filtered and the
filtercnfiwawas successively washed with 10% aqueous solu-
tions of NaHSO3, Na28203, NaHCO3, and finally water. The
solid was dried to give 81 g (90%) of 25, which wasre~
crystallized from chloroform/methanol, mp 2“9-250° (lit.
25l—252°C); 1H NMR (CD013) 6 2.78 (s, 6 H); mass spectrum,
m/g (relative intensity) “22 (100), 3“1 (5“), 262 (25),
182 (21), 102 (67).

 

3. Tetrabromo-p:xylene-d6 (251d6)

In a procedure similar to that used for 25, a sus-
pension of 0.“ g of iron powder in 3.1 g (26 mmol) of p-

xylene d1097

was treated dropwise with 15 mL (0.28 mol)

of bromine. After work-up 11.25 g (98%) of 25-d6 was
'V'b’b'b

obtained which was recrystallized from CHCl3/CH30H;

mp 2“8-250°C; mass spectrum, m/g (relative intensity)

428 (11), 347 (6), 268 (3), 187 (21), 108 (100).

High resolution mass spectrum: Calcd. for 08D6Bru:

425.75562; Found: 425.75693.

98
“. 1,“,5,8,9,lO-Hexamethyl-l,“,5,8-tetrahydroanthracene-

l,“;5,8-bis-endoxide (22)
1\I

 

To a suspension of “.22 g (10 mmol) of 25 and 5 g
(excess) of 2,5-dimethylfuran (28) in 100 mL of dry ether
at —78°C under argon, was added dropwise (2 h) 11 mL
(22 mmol) of n-butyllithium (2 M in hexane) which was
diluted with 100 mL of hexane. After stirring the mixture
for 2 h at -78°C, it was allowed to warm to room tempera-
ture and quenched with methanol (1 mL). The ethereal
solution was washed with water, dried (MgSOu), and concen-
trated. Trituration of the crude product with 10 mL of
hexane gave 2.19 g (73%) of 22 as a mixture of anti:syn
isomers with the ratio of 57:“3. Successive washing of
this mixture with ether yielded a pure sample of the anti

isomer. mp 283-28“°C; l

H NMR (00013) 6 1.94 (s, 12 H),
2.29 (s, 6 H), 6.78 (s, 2 H); mass spectrum, m/g (relative
intensity) 294 (9), 251 (37), 225 (81), 209 (22), 193 (21),
178 (26), 43 (100).

Anal. Calcd. for 020H2202: c, 81.60; H, 7.53.

Found: C,81.51; H, 7.50.

 

In this experiment, when anhydrous toluene was used
as a solvent under otherwise similar conditions, the yield

of 29 was increased to 93% with the same anti:syn ratio.

In this experiment, when only 10 mmol of n-butyllithi-
um was used under otherwise similar conditions, 3.26 g of
a crude reaction product was obtained. Chromatography

of this crude product on an alumina column using hexane

99

as eluent gave 1.35 g (32%) of unreacted tetrabromo-
p-xylene. Further elution with 3:1 hexanezmethylene
chloride gave 1.58 g (“7%) of bis-adduct 29 as a mixture
of anti and syn isomers. No trace of mono-adduct 31

was observed.
5. 2,5-Dibromo-“,6-diiodo-l,“-dimethylbenzene (“6)
mm—

To a solution of “0.8 g (0.11“ mol) of 2,5—diiodo-

1,“-dimethy1benzene98 and 37 g (0.22“ mol) of anhydrous
ferric chloride in 200 mL of nitromethane at 0°C was added
dropwise 16 mL (0.3 mol) of bromine. After the mixture
was left overnight, the white solid was filtered, washed
with nitromethane and acetone to give 52.5 g (89%) of “6
which was recrystallized from ethanol/Chloroform, mp 225—
227°C; 1H NMR (CD013) 6 3.00 (s, 6 H); mass spectrum m/g
(relative intensity) 516 (“), 389 (2), 262 (7), 181 (15),
127 (93), 102 (100), 75 (88), 51 (89). High resolution
mass spectrum: Calcd. for C8H6I2Br2: 513.69305; Found:

513.69202.
6. 2,5-Dibromo-“,6-dichloro—l,“-dimethylbenzene (“7)
W

A solution of “ g (0.025 mol) of anhydrous ferric
chloride and 6.6 g (0.025 mol) of 2,“-dibromo-1,“-
dimethylbenzene99 in 100 mL of nitromethane was poured
into a three-necked flask equipped with a thermometer,
reflux condenser and gas inlet tube. The flask was

cooled in an ice bath and chlorine gas was passed through

100

the solution via a gas inlet tube. As soon as the chlorine
was introduced a white solid precipitated (the reaction

is highly exothermic). Passage of chlorine was continued
for 2 h. The solid was filtered, washed with nitromethane
and acetone and recrystallized from chloroform/methanolto
give “.5 g (5“%) of “7, mp 226°C, (lit.25 226°C); ITINMH
(CDC13) 6 2.62 (s, 6 H); mass spectrum, m/e (relative
intensity ) 337 (“), 335 (31), 33“ (89), 332 (100), 330
(“1), 296 (30), 253 (91), 217 (25), 172 (26), 136 (6“),

101 (““), 75 (55).

7. 2,3,5,6-Tetraiodo-l,“—dimethylbenzene (“8)
mm

This compound was prepared according to the literature

method, by mercuration of p-xylene and iodination of the

mercury compound with I2/KI; mp 2“6-2“8°C (lit.2u

2“8°C); 1

2“5-

H NMR (CDC13) 6 3.30 (s, 6 H); mass spectrum, m/g
(relative intensity) 610 (1), “83 (2), 356 (2), 229 (36),
127 (33), 102 (100), 75 (61)-

8. 1,“,5,8—Tetramethyle6,7-dibromo-l,“-dihydronaphtha-

 

1ene-l,“-endoxide (31)
HA,“

To a suspension of 1.5 g (0.00“ mol) of 51 in 20 mLCm‘
1,2-dich1oroethy1ene was added “ g (excess) of 2,5—dimethy1-
furan and 1.5 mL of propylene oxide. The mixture was
warmed gradually to avoid vigorous CO2 evolution, then was
heated under reflux for 3 h. After the mixture was cooled

to room temperature the solvent was removed by a rotary

101

evaporator. The residue was dissolved in 100 mL of ether
and washed three times with 50 mL portions of 10% aqueous
sodium hydroxide and finally with water and dried (MgSOu).
Concentration of the ether left a brown solid which was
washed on activated alumina, eluting with 3:1 hexane:
methylene chloride to give 1.03 g (71%) of 31 which was

1 mm
H NMR (CDC13)

recrystallized from CH30H, mp l“6-1“7°C;
6 1.98“ (s, 6 H), 2.“82 (s, 6 H), 6.772 (s, 2 H);
130 NMR (00013) 6 18.61, 20.21, 89.64, 126.11, 129.69,
l“6.66, 150.53, mass spectrum, m/e (relative intensity)
361 (0.“), 350 (2), 359 (0.8), 358 (“), 155 (91), 153
(86), 152 (85), 139 (61), 129 (“5), 128 (100), 127
(“8), 115 (57), 77 (“0), 76 (“0).

Ana). Calcd. for ClquuOBr2: C, “6.96; H, 3.9“;
Br, ““.63. Found: C, “7.05; H, 3.95; Br, ““.62.

Compound 31 was also prepared as follows: to a

suspension of “.22 g (10 mmol) of 25 and 5 g (excess) of
2,5-dimethylfuran in 100 mL of dry toluene at —78°C under
argon, was added dropwise (2 h) n—butyllithium (10 mmol)
in 50 mL of hexane. After stirring the mixture for 2 h
at —78°C, it was allowed to warm to room temperature and
quenched with methanol (1 mL). The toluene solution was-
washed with water, dried (MgSOu), and concentrated to
give 3.56 g (100%) of 31 (the physical data of this

compound were similar to that mentioned above).

102

9. 1,“,5,8—Tetramethyl-9,10—dimethyl—d6-l,“,5,8-

 

tetrahydroanthracene—l,“i5,87bis—endoxide (29-d )
Wmmm

 

In a procedure similar to that used for 29, a suspen-
sion of 1.07 g (2.5 mmol) of 25—d6 and 2.5 g (excess) of
’b’b’b
2,5-dimethylfuran in 50 mL of anhydrous ether, was
treated dropwise with 6 mmol of n-butyllithium in 25 mL
of dry hexane over a 2 h period. After work-up and
purification 0.7“ g (98%) of 29-d6 was obtained as a
'b'b'b
mixture of anti and syn isomers with the ratio 61:39.
1H NMR (CDC13) of the mixture: two singlets at 6 1.935
and 1.957 (12 H) correspond to the methyl groups, 2
singlets at 6 6.75“ and 6.785 (“ H) correspond to the
vinyl hydrogens; mass spectrum, m/g (relative intensity)
300 (5), 257 (19), 231 (70), 215 (88), “3 (100). High
resolution mass spectrum: Calcd. for C20H16D6O2:

300.19965. Found: 300.19978.

10. Reaction of mono-adduct 31 and 245-dimethylfuran

WW

 

 

with n-butyllithium

 

To a solution of mono-adduct 31 (0.358 g, 1 mmol) and
2,5-dimethylfuran (0.5 g, excess) in 20 mL of dry ether
at -78°C under argon, was added dropwise 2.5 mmol of
n-butyllithium in 10 mL of dry hexane over 1 h. After
stirring for 3 h at -78°C the mixture was allowed to warm
to room temperature and quenched with methanol (1 mL).
The ethereal solution was washed with water, dried

(MgSOu) and concentrated. Trituration of the crude

103

product with 5 mL of hexane gave 0.288 g (98%) mixture
of the two isomers of 29 with the 57:“3 anti to syn ratio

(for physical data see p. 98).

 

11. Reaction of mono-adduct 31 and tetrabromo-p-xylene
W

(251g6) with n-butyllithium in the presence of

 

2,5-dimethylfuran

 

A solution of 2.1“ g (5 mmol) of 25-d6 and 1.7 g
(5 mmol) of mono-adduct 31 and 5 g (excess) of 2,5-dimeth-
ylfuran in 100 mL of dry ether was cooled to -78°C under
argon (most of the 25-d6 precipitated). To this suspen-
sion n-butyllithium (10 mmol in 50 mL of hexane) was added
dropwise over 2 h. After stirring the mixture for 3 h at
—78°C, it was allowed to warm to room temperature and
quenched with methanol (1 mL). The ethereal solution was
washed with water and dried (MgSOu). Concentration of
the ether at low pressure left 3.106 g of a crude product
which was chromatographed on activated alumina, eluted
with hexane and later 9:1 hexane:methylene chloride to

give as the first fraction, 0.7“6 g (2“%) of unreacted

25-d6. The second fraction, 0.523 g (17%) was a mixture

mmmm

of mono-adducts 31 and 31-d6. The percentage of 3l-d
mm mmmm mmmm5

in this mixture was determined from the proton NMR,
in that the signal corresponding to aromatic methyls
(6 1.98 ppm) was 30-“0% smaller in area than the signal

corresponding to the bridgehead methyls (6 2.“8 ppm).

10“

Also the mass spectrum of this mixture was similar to
that of 31 Q1100 but showed a peak at m/g 363 (trace)
’b’b
corresponding to $386'
Finally, eluting with methylene chloride gave a
1.816 g (58%) mixture of bis-adducts 29 and 29-d6. The
’L’L 'b'b’b'b
percentage of 29-d (30%) in this mixture was determined
m mm6

from integration of the peak at 6 2.92 (aromatic methyls)

compared to peak at 6 1.9“ (bridgehead methyls).

12. Reaction of “7 with n-butyllithium in the presence of
’U

2,5-dimethy1furan

In a procedure similar to that used for bis-adduct
29, reaction of “7 (3.33 g, 5 mmol) and 28 (2.5 g, excess)
'b’b N’b ’b’b
with n-butyllithium (12 mmol) in 100 mL of hexane, gave
0.51 g (35%) of bis—adduct 29 as a 57:“3 mixture of anti

to syn isomers.

13. Reaction of “6 with n-butyllithium in theépresence of
'\J

2,5-dimethy1furan

 

In a procedure similar to that used for bis-adduct 2%,

reaction of “6 (2.58 g, 5 mmol) and 28 (2.5 g, excess) in
100 mL of dry ether at -78°C under argon with n-butyl-
lithium (12 mmol) in 100 mL of hexane gave 1.12 g (76%)

of bis-adduct 29 as a 57:“3 mixture of anti to syn isomers.

105

1“. Reaction of)“8 with n-butyllithium in the presence of

2,5—dimethy1furan

 

In a procedure similar to that used for bis-adduct 2%,
reaction of “8 (3.05 g, 5 mmol) and 28 (2.5 g, excess) in
100 mL of dry ether at —78°C under argon with n—butyli-
thium (12 mmol) in 100 mL of hexane gave 1 g (68%)cmfbis-

adduct 29 as a 61:39 mixture of anti to syn isomers.

15. N-Methyl—l,2,3,“,5,8-hexamethyl-6,7-dibromo-l,“-

dihydro-naphthalene-l,“-imine (52)
1U

A solution of 25 (“.22 g, 10 mmol) and 22 (1.37 g,
10 mmol) in 100 mL of dry toluene under argon was cooled
to —78°C (most of the 25 precipitated). To this suspen~
sion n-butyllithium (12 mmol in 50 mL of hexane) was added
dropwise over a period of 2 h, then the reaction mixture
was slowly warmed to room temperature. The excess n-
butyllithium was quenched with methanol (1 mL). Toluene
was removed on a rotary evaporator and the remaining solid
was dissolved in ether. The ethereal solution was washed
with water, dried (MgSOu) and concentrated to give 3.95 g
of crude product. Chromatography of this crude product on
an alumina column using hexane as eluent gave 3.5 g (88%)
of 52, mp 118-120°C; 1H NMR (CDC13) 6 1.66 (broad s,
12 H), 1.93 (s, 3 H), 2.42 (s, 6 H); 130 NMR (00013)
6 11.13, 15.7“, 20.83, 30.60, 77.0“, 126.06, 132.17,

1“5.“7, 1“9.60; mass spectrum, m/g (relative intensi-
ty) 402 (3), 398 (8), 355 (22), 320 (10), 277 (45), 197

106

(1“), 128 (16), 115 (50), 70 (““), 56 (100); high resolu-
tion mass spectrum: Calcd. for C17H21Br2N: 397.00“18;

Found: 397.00525.

16. N-Methyl—l,2,3,“,5,8,9,10-octamethyl-1,“,5,8-

 

tetrahydroanthracene-1L“-imine-5,8-endoxide(53)

 

In a procedure similar to that used for 22, reac-
tion of the mono-adduct 31 (1.79 g, 5 mmol) and 22 (0.68 g,
5 mmol) in 100 mL of dry toluene with n-butyllitgium
(12 mmol) gave a crude product mixture. Chromatography
of this crude product on activated alumina, eluting with
methylene chloride, gave 0.69 g (“2%) of 53 as a mixture
of two isomers. Separation of the isomers was not
attempted. The 180 MHz proton NMR spectrum clearly
showed the presence of two isomers in the ratio of 60:“0.
1H NMR (00013) of the major isomer, 6 1.65 (s, 6 H), 1.66
(s, 6 H), 1.95 (s, 6 H), 2.03 (s, 3 H), 2.25 (s, 6 H),
6.79 (s, 2 H); 1

(S, 6 H): 1065 (S9 6 H): 1096 (S, 6 H), 2'03 (S: 3 H):

H NMR (CDC13) of the minor isomer, 6 1.61

2.31 (s, 6 H), 6.78 (s, 2 H); mass spectrum, m/e (relative

intensity) 355 (2), 238 (11), 255 (3), 281 (3), 56 (100).

High resolution mass spectrum: Calcd. for C23H29NO:

335.22“92; Found: 335.22506.
The bis—adduct 53 was also prepared as follows: In
a procedure similar to that used above, reaction of mono-

adduct 52 (1.67 g, 5 mmol) and 28 (2.5 g, excess) in

107

100 mL of dry toluene with n-butyllithium (5.5 mmol) gave
1.66 g of a crude product mixture. Chromatography of

this crude mixture on activated alumina eluting with methyl—
ene chloride gave 1.U3 g (86%) of 53 as a mixture of two

isomers in the ratio of 71/29.

17. Bis-(N-methyl)-1,2,3,“,5,8,9,10-octamethyl—1,“,5,8-

 

tetrahydroanthracene—l,U;5,8-bis-imine (5U)
’L’b

In a procedure similar to that used for 29, reaction
of 52 (2.97 g, 7.5 mmol) and N-methyl-2,5-dimethy1pyrrole
(0.817 g , 7.5 mmol) in 100 mL of dry toluene with n—
butyllithium (12 mmol) in hexane gave a crude product
mixture. Chromatography of this crude mixture on activa-
ted alumina, eluting with 3:1 hexane:chloroform gave
0.Ul8 g (2U%) of 53 as a mixture of two isomers. 1H NMR
of the mixture (CDC13) 6 1.63, 1.66, 1.76 (three singlets,
1,2,3,U,5,6-methyls, 18 H), 1.86, 1.90, 1.96, 2.00 (four
singlets, N-methyls, 6 H), 2.18, 2.23, (two singlets,
9,10-methyls, 6 H), 6.60 (broad 3, vinyl hydrogens): mass
spectrum, m/g (relative intensity) 3&8 (5), 293 (15), 278
(12), 268 (29), 238 (23), 220 (9), 205 (27), 56 (100).
High resolution mass spectrum: Calcd. for C2uH
3N8.25656; Found: 3H8.25838.

32N2‘

108

18. l,“,5,6,7,10,11,l2-Octamethyl-1,“,7,10—tetrahydrobi-

naphthylene-l,“37,10-bis-endoxide (55)

To a solution of mono-adduct 3% (1.79 g, 5 mmol) 11150
mL of dry ether at -78°C under argon, was added dropwise
n-butyllithium (2.5 mL, 2 M in hexane) in 25 mL of hexane
over a period of 1 h. After stirring for 6 h at -78°C
the mixture was quenched with methanol (1 mL). The
ethereal solution was washed with water and dried (MgSOu).
Concentration of the ether gave a crude product mixture.
Column chromatography of this crude mixture on activated
alumina eluting with 3:1 hexane:chloroform gave 0.158 g
(8%) of 52 as a mixture of syn and anti isomers. The
major isomer was purified by successive washing of the

mixture with ether, mp 315-317°C; l

H NMR (CDC13) 6 1.90
(s, 12 H), 2.13 (s, 12 H), 6.63 (s, “ H); mass spectrum,
m/g (relative intensity) 396 (“7), 370 (“0), 353 (23),
3““ (55), 327 (100), 310 (“1), “3 (98). High resolution
mass spectrum: Calcd. for C28H2802: 396.20893; Found:

396.21633.

19. 9,10-Dimethy1—1,“,5,8—tetrahydro-1,“55,8-dimethano-

anthracene (76)
W’b

 

A solution of tetrabromo—p-xylene (£5) (“.22 g, 10

mmol) and freshly distilled cyclopentadiene (1.32 g,

109

20 mmol) in 100 mL of dry ether under argon was cooled to
-78°C (most of 25 precipitated out). To this suspension
22 mmol of n-butyllithium in 100 mL of hexane was added
dropwise for a period of 2 h. The mixture was allowed

to gradually warm to room temperature. Reaction was
quenched with methanol (1 mL) and the mixture was washed
with water and dried (MgSOu). After removal of the
solvent (rotovap) the solid residue was washed on an
alumina column with hexane to give 2.27 g (97%) of 16

as a mixture of two isomers, mp 105-107°C; l

H NMR (CDC13)
6 2.13 (m, “ H), 2.20 (s, 6 H), 3.8 (t, “ H), 6.60 (t,
u H); 13C NMR (00013) 6 1u.73, “8.19, 70.02, 122.76,
1“3.31, l“6.58; mass spectrum, m/g (relative intensity) 23“
(69), 219 (100), 203 (2“), 193 (51), 178 (36), 165 (26),
152 (17), 102 (19), 89 (18).

Anal. Calcd. for 018H18‘ c, 92.26; H, 7.7“.

Found: C, 92.28; H, 7.8“.

In this experiment when “0 mmol of n-butyllithium was
used under otherwise similar conditions, the yield of
bis—adduct 76 decreased to 37%.

This reaction was also repeated as follows: to a
solution of cyclopentadiene (1.32 g, 20 mmol) in 100 mL
of dry ether at 0°C under argon, 20 mmol of n—butyllithium
was added (the cyclopentadiene anion precipitated). To

this suspension tetrabromo-p-xylene (“.22 g, 10 mmol) was

added. The reaction mixture was cooled to -78°C and then

110

20 mmol of n-butyllithium in 50 mL of hexane was added
dropwise (2 h). After work-up similar to that mentioned
for 76, the reaction product contained cyclopentadiene
dimer and some polymeric materials. No trace of bis-

adduct 76 was observed.
’L’b

20. 1,“,5,8—Tetrahydro—9,10—dimethyl-ll,l2-bis(l—methyl-

ethylidene)-l,“;5,8—dimethanoanthracene (77)
Wh—

 

In a procedure similar to that used for 76, reaction

NW
100 (2.32 g, 20 mmol) in

of 25 (“.22 g, 10 mmol) with 69
150 mL of dry THFENM322 mmol of n—butyllithium in 100 mL of
hexane gave a yellow solid residue which was chromatograp-
hed on activated alumina. Hexane first eluted 1.7 g of

77 as a single isomer, mp 270-272°C; 1H NMR (CDC13)

6 1.“5 (s, 12 H), 2.26 (s, 6 H), “.33-“.“3 (t, 2 H),
6.66-6.76 (t, u H); 130 NMR (00013) 6 1u.7u, 18.91,
“8.62, 99.89, 121.38, 1“3.28, 1“5.““, 161.38; mass spec-
trum, m/e (relative intensity) 31“ (100), 299 (25),
288 (16), 269 (1“), 2“7 (“5), 232 (15), 215 (21). High
resolution mass spectrum: Calcd. for C2“H26: 31“,203“6;
Found: 31“.20328.

Further elution with hexane resulted in 0.5 g more

of 77 as a mixture of two isomers (total yield 70%).

21. 11,12-Bis(diphenylmethylene)-1,“,5,8-tetrahydro-9,10—

 

dimethyl-1,“;5,8-dimethanoanthracene_78_

 

In a procedure similar to that used for 76, reaction

111

100
of 25 (“.22 g, 10 mmol) with 69

(“.60 g, 20 mmol) in
300 mL of anhydrous THF and 22 mmol of n—butyllithium
gave a white solid which was filtered and washed with
water and dried to give 2 g (36%) of a pure isomer of
78. The product did not melt below 350°C and did not
dissolve in organic solvents suitable for an NMR
spectrum; mass spectrum, m/g (relative intensity) 567
(77), 371 (56), 227 (39), 178 (55), 165 (“0), 152 (18),
191 (100). High resolution mass spectrum: Calcd. for
C““H35:

purify the other isomer were not successful.

562.26605; Found: 562.2670. Attempts to

22. l',“',5',8'-Tetrahydro-9',10'-dimethyldispiro[cyclo-

 

propane-1,ll'-[l,“;5,8]dimethanoanthracene-12',11"-

 

cyclopropane] 79
’L'b—

 

In a procedure similar to that used for 76, reaction
mm

101 (2.3 g, 25 mmol)

of 25, (“.22 g, 10 mmol) with diene 70
in 100 mL of anhydrous toluene and n-butyllithium (22 mmol)
gave a crude product mixture. This crude mixture was
triturated with methanol (20 mL) and filtered to give

2.28 g (80%) of 79 as a mixture of two isomers. Recrystali-
zation of this mixture from methanol/ethyl acetate gave
1.9“ g (68%) of a pure isomer, mp 223-225°c; 1H NMR

(00013) 6 0.50 (m, 8 H), 2.16 (s, 6 H), 3.13-3.23 (t, u H),
6.60—6.76 (t, u H); 13C NMR (00013) 6 8.96, 10.01, 1u.75,
53.8“, 65.13, 121.“3, l“2.72, 1“5.98; mass spectrum, m/e

(relative intensity) 286 (100), 271 (27), 258 (76), 2“1

112

(30), 227 (“3), 215 (53), 202 (““), 11“ (“7), 108 (37).
Anal. Calcd. forC22H18: C, 92.26; H, 7.7“.

Found: C, 92.25; H, 7.77.

23. 1',“',5',8'-Tetrahydro-9',10'-dimethy1dispiro
Lcyclopentane-l,1l'—[1,“;5,8]dimethanoanthracene-

l2',l"—cyclopentane] 0
.m_

v

((1)

In a rocedure similar to that used for 76, reaction

102

of 25 (“.22 g, 10 mmol) with diene 71 (3.6 g, 30 mmol)

’V‘u

in 100 mL of anhydrous THF and n—butyllithium (22 mmol)
gave a crude product mixture. Column chromatography of
this crude mixture on activated alumina, eluting with
“:1 hexane:methylene chloride, gavel”9%%?g(58%) of 80
as a mixture of two isomers. Successive washing of this
mixture with ether gave a pure sample of the major isomer,
mp 222-225°c; 1H NMR (00013) 6 1.00-1.73 (m, 16 H), 2.10
(s, 6 H), 3.33-3.u3 (t, u H), 6.50—6.60 (t, u H); 130 NMR
(00013) 6 1u.76, 25,89, 25.89 (overlap), 33.75, 33.85,
56.98, 90.67, 123.0“, 1“2.79, 1“6.2“; mass spectrum, m/g
(relative intensity) 3“2 (100), 327 (30), 259 (1“),
215 (16),

Anal. Calcd. for C26H30: C, 91.17, H, 8.83.

Found: C, 91.07; H, 8.80.

2“. l,2-Dibromo-3,“,5,6-tetramethy1benzene (21)
mm

This compound was prepared in nearly quantitative

yield according to the Smith and Moyle method,”5 by

113

bromination of prehnitene in carbon tetrachloride using
iron powder as catalyst.
25. 5,6,7,8-Tetramethy1-l,“—dihydro-1,“-methanonaphtha-
lene (81)
In a procedure similar to that used for 76, reaction
of 21 (5.8 g, 20 mmol) with cyclopentadiene (1.32 g,
20 mmol) in 200 mL of anhydrous ether and n-butyllithium
(20 mmol) gave 3.86 g (97%) of 81 which was recrystalized
from methanol; mp 50-52°C; 1H NMR (CDC13) 6 2.05 (s, 6 H),
2.13 (m, 2 H), 3.96 (t, 2 H), 6.63 (t, 2 H); 13c NMR
(00013) 6 15.96, 16.22, “8.83, 68.23, 127.39, 130.52,

1“2.97, 167.87; mass spectrum; m/g (relative intensity)

198 (“0), 183 (100), 172 (10), 168 (10), 165 (12), 157
(21), 153 (13), 141 (17), 128 (11), 115 (1“), 91 (10).

Anal. Calcd. for C C, 90.85; H, 9.15.

15H18‘
Found: C, 90.98; H, 9.05.

26. 5,6,7,8-Tetramethy1-1,“-dihydro-9-(l-methylethyli-

dene)-1,“-methanonaphtha1ene (82)
1D

In a procedure similar to that used for 76, reaction
of 21 (2.92 g, 10 mmol) with 68 (1.06 g, 10 mmol) in 100nfl.
of THF and n-butyllithium (12 mmol) gave a yellow residue
which was triturated with methanol (10 mL) to give 1.36 g
(57%) of 82, which was recrystalized from methanol, mp

1

96-98°c; H NMR (00013) 6 1.50 (s, 6 H), 2.10 (s, 6 H),

2.23 (S, 6 H), “.33-“.“6 (t, 2 H), 6.60-6.20 (t, 2 H);

11“

130 NMR (00013) 6 16.01, 16.20, 18.99, “9.20, 101.21,
126.56, 130.90, l“2.86, 1“5.79, 160.39; mass spectrum,
m/e (relative intensity) 238 (100), 223 (27), 208 (13),
193 (11), 171 (17). High resolution mass spectrum:

Calcd. for C18H22: 238.17215; Found: 238.17252.

27. 5,6,7,8-Tetramethylel,“-dihydro-9-(diphenylmethylene)-

 

1,“-methanonaphthalene (83)
mm—

In a procedure similar to that used for 16, reaction
’1;
of 21 (2.92 g, 10 mmol) with 69 (2.30 g, 10 mmol) in
’b’b ’VL
150 mL of dry THF and 12 mmol of n—butyllithium gave a

crude product which was triturated with methanol (20 mL)
and filtered. Chromatography of the remaining solid on
activated alumina, eluting with hexane, gave 2.3 g (62%)

of 83, mp 177-178°C; 1
mm

H NMR (00013) 6 2.13 (s, 6 H), 2.20
(s, 6 H), “.“0-“.50 (t, 2 H), 6.76-6.86 (t, 2 H), 6.86-
7.16 (m, 10 H); mass spectrum, m/g (relative intensity)
362 (“5), 191 (75), 171 (100), 165 (60), 158 (88).

Anal. Calcd. for C28H26: C, 92.77; H, 7.22.

Found: C, 92.73; H, 7.21.

28. 5',6',7',8'-Tetramethy1-1',“'-dihydrospiro[cyclopro-

Bane-1,9'-[1,“]-methanonaphtha1ene] (8“)
'U

In a procedure similar to that used for Z6, reaction
'\1
of 21 (2.92 g, 10 mmol) with diene 70 (1.5 8, 16 mmol) in
mm
100 mL of anhydrous toluene and n-butyllithium (12 mmol)

gave a crude mixture which was chromatographed on activated

115

alumina. Hexane first eluted some butylated compounds.
Further elution with hexane gave 1.62 g (73%) of 8“,
which was recrystalized from methanol, mp 106-107°C; 1H
NMR (00013) 6 0.53 (m, u H), 2.10 (s, 6 H), 2.16 (s, 6 H),
3.30-3.u0 (t, 2 H), 6.66—6.76 (t, 2 H). 13c NMR (00013)
6 15.93, 16.16, 5“.26, 63.25, 126.88, 130.28, 1“2.31,
1“6.55; mass spectrum, m/g (relative intensity) 22“ (9“),
209 (7“), 196 (100), 181 (56), 165 (“5), 1“9 (27).

Anal. Calcd. for C17H20: C, 91.01; H, 8.99.

Found: C, 90.80; H, 9.08.

29. 5',6', [,8'-Tetramethy1-1'“'—dihydro-spiro[cyclopen—

tane 1,9'—[1,“j-methanonaphthalene] (85)
mm’

 

In a procedure similar to that used for 76, reaction
of 21 (2.92 g, 10 mmol) with diene 71 (1.8 g, 15 mmol)
in 100 mL of THF and 12 mmol of n-butyllithium gave a
crude product mixture. Chromatography of this crude
mixture on activated alumina, eluting with “:1 hexane:
methylene chloride gave 1.32 g (52%) of 85, mp 95-97°C;
1H NMR (00013) 6 1.10-1.70 (m, 8 H), 2.06 (s, 6 H), 2.16
(s, 6 H), 3.“3-3.60 (t, 2 H), 6.“3—6.60 (t, 2 H); 13c NMR
(00013) 6 16.00, 16.23, 25.60, 25.60 (overlap), 33.5“,
33.80, 57.79, 88.37, 127.5“, 130.11, l“2.70, 16“.99;
mass spectrum, m/g (relative intensity) 252 (100), 237
(“9), 223 (8), 208 (10).

Anal. Calcd. for C19H2u: C, 90.“1; H, 9.59.

Found: C, 90.28; H, 9.“8.

116

30. 6,13-Dimethyl-5,7,12,1“—tetrahydro-5,1“[l',2'127,12-

[1",2"]-dibenzengpentacene 86 (F = CH3l
'b

 

To a stirred suspension of 2.11 g (5 mmol) of tetra-

bromo—p—xylene and 1.78 g (10 mmol) of anthracene in 250 mL

of dry toluene under argon at -10° was added dropwise

(1)

over “ h 12 mmol of n—butyllithium in 100 mL of hex ne.

The mixture was allowed to gradually warm to room tempera-
ture. The reaction was quenched with methanol and the
mixture was washed with water and dried (MgSOu). After
rem:val of the solvent (rotovap) the solid residue was
chromatographed on silica gel. Hexane eluted the
unreacted anthracene (1.07 g). Further elution with 9:1
hexane:methylene chloride gave 0.327 g (0.71 mmol, 35%
based on consumed anthracene) of 86 (R = CH3) which was
recrystallized from chloroform, mp “60—“62°C. 1H NMR
(CDC13) 6 2.65 (s, 6 H), 5.59 (s, “ H), 6.90 (m, 8 H),

7.28 (m, 8 H); 13

c NMR (00013) 6 1“.36, 50.8“, 123.u3,
12“.32, 125.01, 1“0.“8, l“5.75; mass spectrum, m/g
(relative intensity) “58 (88), ““3 (“1), “27 (30), 280
(100), 265 (3“), 229 (80), 21“ (66), 221 (“9), 178 (53);
UV (CH3CN) Xmax 232 nm (log a “.66), 261 (3.75), 278 sh
(3.66); IR (KBr) 3010, 3000, 1“65, 1“60, 750 om'l.
Anal. Calcd. for C36H26: C, 9“.28; H, 5.72;

Found: C, 9“.16; H, 5.71.

 

117

31. 6,13—Dimethoxy-5,7,12,1“-tetrahydro-5,1“[l',2'3:7,12-

 

[1",2"]-dibenzenopentacene 82 (R = OCH32

The procedure and scale were identical to that used
for 86 (H = CH3). After recovery of the unreacted anthra-
cene (0.88 g) by elution with hexane, further elution
with “:1 hexane:methylene chloride gave first 0.375 g
(1.19 mmol, 21%) of l,“-dimethoxytriptycene (93), mp 238-
2“0°C (lit.103 value 239-2“1°C); 1H NMR (CDC13) 6 3.73
(s, 6H), 5.76 (s, 2 H), 6.33 (s, 2 H), 6.83 (m, “ H),

7.20 (m, “ H); mass spectrum, n/a (relative intensity)
31“ (62), 283 (100), 252 (35), 239 (5“), 1“9 (“8), 1“2

(71), 85 (6“), 83 (93). Continued elution with the same

solvent gave 0.511 g (1.0“ mmol, 37%) of 86 (H = 0CH3)

which was recrystallized from acetonitrile, mp “OD-“02°C;

1H NMR (CDC13) 6 3.76 (s, 6 H), 5.50 (s, “ H), 6.73 (m,

8 H), 7.10 (m, 8 H); 130 NMR (00013) 6 “8.23, 62.85,

123.55, 125.23, 136.38, 1“5.3“, l“7.00; mass spectrum,

m/a (relative intensity) “90 (19), “59 (9), 283 (100),

222 (22), 21“ (1“), 202 (12), 178 (15); UV (CH3CN)

Amax 277 nm (log a 3.71), 261 (3.93); IR (KBr) 2920, 2820,

1“60, 1050, 1300, 1260, 10u5, 755, 790 cm‘l.
Anal. Calcd for C36H26O2: C, 88.13; H, 5.3“.

Found: C, 88.25; H, 5.36.

118

32. 6,13-Dihydroxy-5,7,12,1“—tetrahydro-5,l“[l',2:J;7,12-

 

[ll,2"]dibenzenopentacene 86 (R = OH)
'b'b

 

 

A solution containing 100 mg (0.20 mmol) of 86 (R =
OCH3) in 30 mL of glacial acetic acid and 10 mL of “7%
hydrogen iodide was heated at reflux for 2 h. The cooled
solution was extracted with chloroform and the combined
organic layers were washed successively with water, aque-
ous sodium bisulfite, aqueous sodium bicarbonate, water
and dried (MgSOu). Removal of the solvent (rotovap) left
90 mg (97%) of 86 (H = OH) as a white solid which becomes
gray at about 300°C and melts with decomposition at “27-

“30°C. 1

H NMR (CDC13) 6 “.“0 (br S, 2 H), 5.50 (S, “ H),
6.76 (m, 8 H), 7.20 (m, 8 H); in DMSO-d6, 6 5.63 (s, “ H),

6.66 (m, 8 H), 7.06 (m, 8 H), 8.“0 (s, 2 H); 0v (CH 0H)

3

Amax 398 nm (log a “.61), 278 (“.82), 262 (“.92); mass

spectrum n/a (relative intensity) “62 (7“), ““5 (39),
28“ (32), 230 (“2), 202 (100), 178 (80); IR (KBr) 3500,
l“70, 1“60, 1220, 750 cm-1. The compound is not very

stable in air and oxidizes slowly to the corresponding

quinone.

 

119

 

 

33 5L7,12,1“-Tetrahydro-5,1“[l',2']:7,12[l",2"]dibenzeno-
pentacene-6,13-dione (90)
”MW-
A solution containing 36 mg (0.078 mmol) of hydro-
quinone 86 (R = CH) and 0.5 g of ceric ammonium nitrate

’b ’10

in 100 mL of acetonitrile was stirred at room temperature
for 2 h. The solvent was removed (rotovap). The residue
was extracted with chloroform and the organic layers

were washed with water (3X) and dried (MgSOu). Removal

of the chloroform and recrystallization from the same
solvent gave 31 mg (86%) of 90 which, upon heating,

became gray at about 270°C and slowly turned black but did
not melt up to 510°C. 1H NMR (C0013) 6 5.60 (s, “ H),
6.76 (m, 8 H), 7.16 (m, 8 H); 130 NMR (00013) 6 07.07,

12“.31, 123.52, 1“3.77, 151.06, 180.02; UV (CH CN) Am

3
270 nm (log a “.76), 279 (“.73); mass spectrum, n/a (rela-

ax

tive intensity) 260 (11), 230 (“8), 202 (100), 178 (92);
13 (KBr) 1650, 1u75, 1“60, 765, 755, 7u5 cm-l.

2002: c, 88.67; H, “.38.

Found: C, 88.57; H, “.“9.

Anal. Calcd. for C3“H

 

120

3“. ,6l7,1“,15—Tetramethy1-5,8,l3,l6-tetrahydro—5,16—

[1',2']:8,13[1",2"]dibenzenohexacene (95)
'b’L-

The procedure and scale were the same as with 86
’b’b

(R = CH3), but using 9“ and anthracene. Chromatography
of the crude product over silica gel and elution with

hexane gave 0.“1 g (2.08 mmol) of recovered anthracene.
Further elution with “:1 hexane:methylene chloride gave
1.607 g (3.0 mmol, 75%) of 95 which was recrystallized

from methanol/chloroform, mp 358-360°C. l

H NMR (00013)

6 2.66 (s, 12 H), 5.60 (s, “ H), 6.76 (m, 8 H), 7.16

(m, 8 H); 13C NMR (00013) 6 20.u1, 50.57, 123.52, 125.25,
132.95, 1“0.69, 1“5.00 (2 0'5); mass spectrum, n/a (rela-
tive intensity 536 (12), 253 (22), 2u6 (23), 238 (8),

83 (62), 57 (50), “u (100); UV (CH3CN) Amax 277 nm (log 0
5.09), 273 (5.06), 259 (“.89); IR (KBr) 3000, 2900, 1“60,

770, 750, 720 cm-1. High resolution mass spectrum:

Calcd. for Cu2H32: 536.2“855; Found: 536.250“1

35. “,5-Dibromo—3,6-diiodo-o-xylene (9Zl
’b

A solution of 16 g (0.0606 mol) of “,5-dibromo-a-
xylenelou and “2 g of mercuric oxide in 160 mL of trifluo-
roacetic acid was heated at reflux for “ h (a white preci-
pitate was formed after about 2 h).105 The solution was
cooled, and the white solid was filtered and subjected

directly to iodination without purification. A mixture

 

121

of iodine (60 g), potassium iodide (“0 g) and the crude
“,5-dibromo-3,6-di(trifluoroacetatomercuri)-a-xylene in

200 mL of water was heated to 70-75°C with stirring for

8 h, cooled and filtered. The solid product was dissolved
in chloroform, washed successively with 10% aqueous sodium
bisulfite, sodium bicarbonate and water, then dried

(N377 ). Removal of the solvent (rotovap) anu recrystal-
lization from chloroform gave 25.5 g (81%) of 97, mp 239—
l

“0°C. H NMR (CZCIB) 6 2.66 (5); mass spectrum, n/g

rel tive intensity) 516 (2), 390 (17), 263 (15), 182 (20),

A
5))

102 (100), 71 (61), 51 (6“).

,7 .- p . .
Anal. Calcd. for C8“6Br212' C, 18.62, H, 1.17.

Found: C, 18.72; H, 1.19.

36. 6,7-01methyl-5,8,13,:u—tetrahydr0-531“[1',2'lt8,13-

[1",2"Jdibenzenopentaphene 87 (R = CH3l
’b'b

The procedure and scale were the same as with 86
(R = CH3) except that the reaction was carried out at
—23°C. Reaction of 91 (2.56 g, 5 mmol) and anthracene
(1.78 g, 10 mmol) with n-butyllithium gave a crude product.
Chromatography of this crude product on silica gel and
elution with hexane gave 1.13 g (6.3“ mmol) of recovered
anthracene. Further elution with “:1 hexane:methylene
chloride gave 0.322 g (0.70 mmol, 38%) of 87 (R = CH3)
which was recrystallized from methanol/chloroform, mp

1

382-38“°C. H NMR (00013) 6 2.33 (s, 6 H), 5.50 (s, 2 H),

5.83 (s, 2 H), 6.83 (m, 8 H), 7.23 (m, 8 H); 130 NMR

122

(CDC13) 6 15.32, 50.18, 50.93, 123.“2, 123.61, 125.15,
125.21, 127.20, 136.31, 139.53, l“5.52, 1“5.53; mass
spectrum, n/a (relative intensity) “58 (97), ““3 (5),
280 (100), 178 (52); IR (KBr) 2900-3050, 1““5, 1380,
750, 720, 690, 620, 610 cm-1; UV (CH3CN) 1 , 227 nm

max
(log a “.70) 262 sh (3.91), 269 sh (3.89), 277 sh (3.83).

High resolution mass spectrum: Calcd. for C3’H26:
0

“58.20318; Found: “58.203“6.

 

6

37- 11’ChlorT-EB10-dihydro-9,10-ethenoanthracene (91220 E
'L’b

To a solution of potassium a—butoxide prepared from)
3.9 g (0.1 mol) of potassium in 200 mL of a-butanol, under
argon, was added 6.5 g (0.023 mol) of anana—11,12—dichloro-
9 , 10-dihydro— 9 , 1 0-<~::hen-oanthracene106 and the mixture was
refluxed for 1 h. After cooling to room temperature
20 mL of water was added and the solvent was removed
under reduced pressure (rotovap). The remaining solid
was dissolved in 200 mL of ether, washed with water

(3 X 50 mL) and dried (MgSOu). Removal of the ether left

5.0 g (88%) of gl which was recrystallized from methanol,
mp 128°C (lit.106 127.5-128°C). 1H NMR (001,) 6 “.80
(d, C10-H, a = 3H2), “.96 (o, C9-H, a = 7.5 Hz), 6.56
(dd, C12-H, l = 3.75 Hz), 6.66-7.20 (m, 8 H); mass
spectrum, n/a (relative intensity) 2“0 (8), 238 (2“),

203 (100), 1“9 (16), 101 (22).

123

38. ll—Chloro-12-deuterio-9,10-dihydro-9,10-

ethenoanthracene (100)
'V’L'b-

 

To a solution of El (0.5 g, 2.1 mmol) in anhydrous
THF (50 mL) at -“2°C under argon was added 2 mL (2.5 mmol)
of E—butyllithium (1.3 M in pentane). The mixture was
stirred for 2 h then warmed to 0°C. CH3OD (1 mL) was
added. The solvent was removed on a rotary evaporator
and the residue was taken up in ether, washed with water
and dried (MgSOu). The ether solution was concentrated
to give 0.5 g of lgg, mp 128-129°C (from methanol); NMR
(001,) 6 “.86 (s, C10-H), “.93 (s, C9-H), 6.60-7.33 (m,

8 H); mass spectrum, n/a, (relative intensity) 2“1 (10),

239 (32), 20“ (100).

LU
\ LI)

12-Chloro—9,10-dihydro-9,10-ethenoanthracene—11-

 

carboxylic acid (99l
'\J

Metalation of 91 in a similar manner and on the same
’b’b

scale as for 100 followed by pouring the resulting 98

mmm mm
over a slush of dry ice and 100 mL of anhydrous ether
gave, on workup by extraction with 10% sodium hydroxide
and acidification to pH 2, 0.3 g (50%) of the known

chloroacid 99, mp 259-260°C (111:.59’107 260-261°0).

“0. ll—Chloro-12-methyl—9,lO-dihydro-9,10-ethenoanthra—

 

cene (101)
—“""—'\a’\l’b-

Metalation of 91 as for 100 was followed by cooling
’L 'L ’b’b’b

 

12“

the resulting solution of 98 to -78°C and the addition of
methyl iodide (1 mL). After the mixture was quickly
warmed to room temperature the solvent was removed
(rotovap), and the residue was taken up in ether, washed
with water and dried (MgSOu). The ether solution was
concentrated to give 0.53 g (100%) of lgl which was

108

recrystallized from methanol, mp 20“-205°C (lit. 206-

1

208°C). H NMR (001“) 6 1.90 (s, 3 H, methyl), “.63

(s, 1 H, bridgehead), “.76 (s, l H, bridgehead), 6.66-

1.20 (m, 8 H, aromatic); mass spectrum, n/a (relative

intensity) 252 (32), 217 (100), 202 (33).

£1, ll-Bromo-12-ch1oro19,10-dihydro—9,10-

 

ethenoanthracene (l02)
fib’b’b”

The procedure described for lgl was followed but with
1 mL of 1,2-dibromoethane in place of methyl iodide, to
give after similar workup 0.“8 g (72%) of lgi after recrys-
tallization from methanol, mp 173-175°C; 1H NMR (CClu)
6 “.86 (s, l H), “.90 (s, 1 H), 6.60-7.23 (m, 8 H); mass
spectrum, n/a (relative intensity) 318 (2), 281 (10),
237 (66), 202 (100); High resolution mass spectrum:

Calcd. for C BrCl: 315.96715; Found: 315.96550.

16H10

“2. 5,6,11,12,17,18—Hexahydro—5,18[1',2']:6,11[1",2"]:

12Ll7[1m ,2” ]tribenzenotrinaphthylene (88)
—vb'—

To a solution of gl (1.0 g, “.2 mmol) in anhydrous

 

rs

 

125

THF (70 mL) at —“2°C under argon was added “ mL (5 mmol)
of a-butyllithium (1.3 M in pentane). The mixture was
stirred at —“2°C for 2 h, then quickly warmed to room
temperature and heated at reflux for 2 h. The mixture

was cooled to room temperature and quenched with metha—
nol (2 mL). The resulting white precipitate was filtered,
washed with water and dried to give 0.169 g (20%) of 88.

1H NMR (00013) 6 6.18 (s, 6 H, bridgehead protons), 6.92

(m, 12 H), 7.u5 (m, 12 H); 13

C NMR (CDC13) 6 “8.6“, 123.“2,
125.01, 135.33, 1“5.36; mass spectrum, n/a (relative
intensity) 606 (100), “28 (82), 256 (“), 178 (19).

The filtrate after removal of 88 was concentrated
on a rotary evaporator. The resulting brown solid was
taken up in chloroform, washed with water and dried
(MgSOL). The residue which remained after removing the
chloroform was chromatographed on alumina with a 3:1

hexanezchloroform eluent to give 0.36 g (39%) of l03

mp 266-268°C (11t.59 268°C).

“3. 9110[1',2']-Benzeno-1,“-dimethy1-l,“—epoxy-1,“lg,

10-tetrahydroanthracene (105l
W'b’b

To a solution of 98 (1.0 g, “.2 mmol) in anhydrous
THF (50 mL) at —“2°C under argon was added “ mL (5 mmol)
of Erbutyllithium (1.3 M in pentane) and the mixture
was stirred for 2 h. This solution was transferred by

syringe to a dropping funnel equipped with a cooling

126

jacket (at -“2°C), and was added dropwise over 1 h under
argon to a refluxing solution containing 5 g of 2,5-
dimethylfuran in 100 mL of anhydrous THF. After 1 h of
additional reflux, the solution was cooled and quenched
with methanol (2 mL). The solvent was removed on the

rotary evaporator and the residue was taken up in ether,

Fl

washed with water and dried (MgSOu). The ether was
removed to give a yellow solid which was chromatographed
over alumina (using first hexane, then “:1 hexanezchloro-
form as eluent) to give 0.50 g (“0%) of 105, mp 179-180°C;

1 L

H NMR (001“) 6 1.63 (s, 6 H, methyls), “.70 (s, 2 H, *—

 

ridgehead), 6.00 (s, 2 H, vinyl), 6.“0—7.l6 (m, 8 H,
arom); 13c NMR (coc13) 5 15.8“, 50.93, 91.7“, 123.03,

1 3.32, 12u.3u, 12u.86, 1“5.01, 1“5.25, 1M5.57, 168.59;

R)

:3

to
U)

A

s spectrum, m/e (relative intensity) 298 (100), 283
(55), 272 (35), 255 (87), 239 (67), 229 (36), 215 (23),
202 (“0), 178 (50). High resolution mass spectrum:

Calcd. for 022H180: 298.13577; Found} 298.13630.

““. 6,ll[l',2'J—Benzeno-5,12-diphenyl-5,12-epoxy—536-

ll,l2—tetrahydronaphthaceneg(lgé)

The same procedure used for 102 was followed, but
using 1,3-diphenylisobenzofuran (1.13 g, “.2 mmol) as
the trapping agent. Chromatography of the crude product
on alumina with hexane as eluent gave 0.32 g of unreacted

l,3-diphenylisobenzofuran. Further elutin with 3:1

127

hexanezchloroform gave 1.21 g (61%) of 106, mp 208-209°C.
1H NMR (001“) 6 5.00 (S, 2 H, bridgehead), 6.20-7.60

(m, 22 H, arom); 13C NMR (00013) 0 51.86, 9“.35, 120.82,
123.06, 123.“2, 12“.“u, 125.08, 128.82, 128.97, 13u.53,
1““.65, 1“5.“3, 150.“6, 167.75 (four peaks are overlapped);
mass spectrum, m/e (relative intensity) “72 (100), 395(15),
265 (20), 178 (21); High resolution mass spectrum:

Calcd. for C 6H

3 2“0: “72.18272; Found: “72.17913.

15, 9,10[1',2'J-Benzeno-ll,ll-dimethoxy-l,2,3,“-tetra-

 

chloro-1,“-methano-l,“,9,10-tetrahydroanthracene

 

(107)

—’\J"\J’b—

The same procedure used for 122 was followed, but
using 5,5-dimethoxytetrachlorocyclopentadiene (1.10 g,
“.2 mmol) as the trapping agent. Chromatography of the
crude product on alumina with hexane as eluent removed
the unreacted diene (0.2 g). Further elution with 3:1
hexanezchloroform gave 0.82 g (“2%) of 101 as a yellow
oil. Further purification by preparative tlc on alumina

gave pure 107, mp l“l-1“2°C; l
’V'VL

H NMR (001“) 5 3.16 (s,
3 H, methoxyl), 3.36 (s, 3 H, methoxyl), “.95 (s, 2 H,
bridgehead), 6.66-7.30 (m, 8 H, arom); 130 NMR (CD013)
6 51.65, 55.28, 59.38, 105.39, 123.“0, 123.68, 125.16,
125.57, l3“.23, l“3.73, 1““.39, l“6.50, mass spectrum,

g[§ (relative intensity) “66 (6), “29 (2), 393 (2),

128

 

26“ (15), 229 (35), 203 (70), 178 (100), 101 (15); High

resolution mass spectrum: Calcd. for C23Hl601“02:

“63.99135; Found: “63.990“5.

“6. 9,10-Dimethyl-l,“,5,8-tetrahydrophenanthrene-1,“35,8-

bis—endoxide l27_
’VL’L

 

To a stirred suspension of “,5-dibromo-3,6-diiodo-o-
xylene 9; (2.16 g, 5 mmol) and furan (2 g, excess) in dry

toluene (100 mL) under argon at -78°C was added dropwise

 

over “ h 12 mmol of n-butyllithium in 100 mL of hexane.

The mixture was allowed to gradually warm to room tempera-
ture. The reaction was quenched with methanol (1 mL) and
the mixture was washed with water and dried (MgSOu). After
removal of the solvent (rotovap) the solid residue was
chromatographed on alumina, eluting with 1:1 hexanezchloro-
form,to give 0.85“ g (71%) of 121 as a mixture of syn

and anti isomers, mp 260—262°C. l

H NMR (CD013) 5 2.13
(s, 6 H), 5.60 (broad s, “ H), 6.80 (broad s, “ H); mass
spectrum m/e (relative intensity) 238 (27), 181 (“6),

167 (100), 165 (85), 152 (“1), 115 (“6).

“7. Hydrogenation of 127
xxx-

 

A solution of 127 (1.19 g, 5 mmol) in 100 mL ofethyl
acetate was hydrogenated forllh over 0.5 g of 10% palladium

on charcoal atrwxm1temperature and “5 p.s.i. of hydrogen.

129

The catalyst was filtered and the solvent was removed
(rotary evaporator). The remaining oil was crystallized
from hexane to give 1.075 g (89%) of 128, mp 162-16“°C.
1H NMR (00013) 0 1.16-1.“3 (m, 8 H), 2.13 (broad s, 6 H),
5.33 (m, “ H); mass spectrum, m/g, (relative intensity)

2“2 (6), 21“ (27), 185 (100), 128 (7); with chemical

C C ‘ +
ionization, (M + 1) = 2“3.

“8. 9,lO-Dimethylphenanthrene (129)
’b’b'b—

 

A solution of 28 (1.07 g, “.“ mmol) in 100 ml of

(0 8H

absolute ethanol wa saturated with HCl (hydrogen

chloride was bubbled through the solution for 10 minutes).
The mixture was heated at reflux for 2 h. After cooling

to room temperature the solvent was removed (rotovap).

The residue was taken up in chloroform (100 mL) and washed
with a 10% aqueous sodium bicarbonate and water and

dried (HgSOu). Removal of the chloroform left a residue
which was washed through a silica gel column. Elution with
hexane gave 0.85“ s (95%) of 129. Recrystallization of

129 from methanol gave a sample with mp l“0°C (lit.79

1“0.5°c). 1H NMR (00013) a 2.66 (s, 6 H), 7.50 (m, u H),
8.0 (m, 2 H), 8.53 (m, 2 H); mass spectrum, m/g (relative
intensity) 206 (100), 191 (82), 178 (12), 165 (32); 130

NMR (00013) 15.86, 122.75, 12u.5“, 125.38, 126.51, 129.2“,

129.“3, 132.21.

 

130

“9. 1,“,5,8,9,lO-Hexamethyl-l,“,5,8-tetrahydrophenan-

threne-l,“;5,8—bis-endoxide 130
'u’b’b"

 

The same procedure and scale was followed as for 129
’VVL

but 2,5-dimethylfuran (2 g, excess) was used as the diene.

Chromatography of the crude product on alumina eluting

 

with 1:1 hexanezchloroform resulted in separation of the

syn and anti isomers. The first fraction (130a), 0.3 g ,
'b 'b’b _.

(20%), was the major isomer, mp 167-168°C. 1H NMR

(0001,) 8 1.86 (s, 6 H), 1.90 (s, 6 H), 2.13 (s, 6 H),

r- v 13 Y"
6.50 (s, u h); c NHH (00013) 8 1“.30, 19.15, 20.27,

 

88.51, 89.31, 125.9“, 1“0.95, 1u6.27, 1u6.53, 1“7.01;
mass spectrum, m/g (relative intensity) 29“ (“), 268 (1“),
251 (86), 2“2 (25), 225 (“3), 208 (100), 193 (23), 178
(21).

The second fraction (130b), 0.20“ g (1“%), mp 166-

mmmm
1

168°C; H NMR (00013) 8 1.96 (s, 6 H), 2.00 (s, 6 H),
2.13 (s, 6 H), 6.“3 (dd, g = 12, u Hz, u H); 13c NHH
(00013) 8 1“.“8, 19.0“, 19.19, 89.9“, 89.35, 126.12,
1“1.02, 1“5.18, 1“5.“9, l“6.18; mass spectrum, m/g (rela-
tive intensity) 29“ (3), 268 (6), 251 (“5), 2“2 (16),

225 (26), 209 (100), 193 (21), 178 (15).

50. H d t1
_y rogena on of_légb (131)

 

A solution of légb (100 mg)ix1100 mLcfi‘ethyl acetate
'b

was hydrogenated for 0.5 h over 100 mg of 10% palladium

on charcoalzn;room temperature and “5 p.s.i. of hydrogen.

131

The catalyst was filtered and the solvent was removed

(rotovap). The remaining oil was crystallized from

 

methanol to give 90 mg (89%) of 131, mp 13“-135°C. lH
’b’b

NMR (CDC13) 6 1.20—1.73 (m, 8 H), 1.86 (S, 6 H), 1.90
(s, 6 H), 2.23 (s, 6 H); mass spectrum, m/e (relative
intensity 298 (1.“), 270 (19), 2“2 (100); with chemical

ionization, (M + l)+ = 299. :-

Bis(N-dimethylamino)-l,“,5,8,9,10—hexamethyl-l,“,5,8-

KW
F—J

 

 

tetrahydrophenanthrene-l,“;5,8-bis-imine (136)
'U

 

The same procedure and scale was followed as for

W

127, but using pyrrole 13“ (1.38 g, 10 mmol) as

mmm mmm

the diene. The crude product was triturated with hexane
(20 mL) to give 0.“5 g (2“%) of 136 (single isomer), mp

187-189°C. 1

H NEH (00013) 0 1.80 (s, 6 H), 1.83 (s, 6 H),
2.16 (s, 6 H), 2.28 (broad s, 12 H), 6.“3 (broad s, “ H);
13C NMR (00013) 8 18.93, 18.72, 19.83, 85.69, 78.71, 76.15,
l26.““, l“5.75, l“6.00, l“6.52, 1“6.75; mass spectrum,

g/g (relative intensity) 321 (58), 276 (92), 262 (100),

116 (32); with chemical ionization (M + l)+ = 379.

The oily residue remaining from concentration of the
hexane solution was chromatographed on alumina. Hexane
eluted the unreacted pyrrole. Further elution with
chloroform gave 0.“32 g (22%) of 136 as a mixture of

W’L'b
isomers (total yield “6%).

 

132

52. Bis(N—dimethylamino)-l,2,3,“,5,6j7,8,9,10-decamethyl-

1,“,5,8—tetrahydrophenanthrene-l,“;5,8-bis—imine (137)

'VVL"

 

The same procedure and scale was followed as for 127
but pyrrole 135 (1.9 g, 10 mmol) was used as the diene.
The crude product was triturated with hexane (20 mL) to
give 0.35 g (16%) of 137 (single isomer), mp 17“-l75°C.
1H NMR (00013) 8 1.56 (s, 6 H), 1.60 (s, 6 H), 1.76 (s,

6 H), 1.80 (s, 6 H), 2.16 (s, 6 H), 2.83 (s, 12 H); 13C
NMR (00013) 6 10.50, 11.38, 1“.77, 17.63, 18.69, 76.12,
76.30, “5.83, 125.68, 1“1.50, l“5.16, 1“5.95, 1“8.21;
mass spectrum, m/g (relative intensity) 318 (100), 30“
(9), 288 (13); with chemical ionization (H + 1)+ = “35.

The oily residue remaining from concentration of the
hexane solution was chromatographed on alumina. Hexane
eluted the unreacted pyrrole 135. Further elution with

'b'b’b

chloroform gave 0.61“ g (28%) of 137 as a mixture of
"\J’b’b

isomers (total yield ““%).

53. 1,“,5,8,9,10-Hexamethylphenanthrene (132)

mmm‘

 

Bis-adduct 136 (50 mg) was sealed under vacuum
(0.1 torr) in a small tube. The tube was heated in an
oil bathzfi:150°C for l h. After the tube was cooled to
room temperature the residue was washed on alumina with
hexane to give 31 mg (90%) of 122, which was recrystal-
lized from methanol, mp 85—86°C. 1H NMR (00013) 6 2.““9

(s, 6 H), 2.631 (s, 6 H), 2.817 (s, 6 H), 7.171 (ABquartet,

 

 

 

133

8 H); 13C NMR (00013) 8 20.79, 22.02, 25.87, 126.08,
129.69, 130.11, 130.59, 131.58, 132.93, 138.68; mass
spectrum, m/g (relative intensity) 262 (100), 2“7 (l3),

, 217 (10); IR (KEr) 285 , 2900, 1850, 1360, 800,
790 cm ; UV (heptane) Amax 32“ nm (log 6 “.“3), 266

;,, 281 (8.68).

Anal. C

W

1cd. for C H : C, 91.55; H, 8.“5.

0
Found: C, 91.

\fl

 

Decamethylphenanthrene (138)
”LN/b—

Pyrolysis of 137 (100 mg) at 170-180°C for 2 h
(using the same procedure as for 132) gave a crude resi-
e. This residue was washed on alumina with hexane to
give 6“ mg (97%) of 138 which was recrystallized from
methanol/chloroform, mp 165-167°C. lH NEH (CDC13) 6
2.33 (broad s, 18 H), 2.“6 (s, 6 H), 2.53 (S, 6 H); in
D6 at 180 M Hz 8 2.227 (s, 12 H), 2.356 (s, 6 H),

68 (s, 6 H), 2.891 (s, 6 H); 13c NMR (00013) 8 16.57,
20.88, 21.08, 21.96, 128.15, 128.98, 130.06, 131.73,
133.73, 13“.38 (two methyls and two sp2 carbons are
overlapped); mass spectrum, m/e (relative intensity)

318 (100), 303 (7), 228 (17), 273 (18); UV (heptane)
Amax 325 (log 5 “.1“), 277 (“.73).

Anal. Calcd. for C C, 90.50; H, 9.50-

28H30‘
Found: C, 90.69; H, 9.50.

 

 

13“

55. Reaction of 131 or 132 with HCl

'V'L'L ’b’b'b

 

 

A solution of 131 (100 mg) in 50 mL of absolute
’b’b'b

ethanol was saturated with HCl gas. This solution was

heated at reflux for 2 h. After similar work-up as for

129, 65 mg of a viscous oil remained. Preparative GLC
’L’L’b

(10% SE-30 on chromosorb w, 200°C) gave two main fractions.

The first frac ion (25%) was hexamethylphenanthrene 132.

The second fraction (75%) was the rearranged product

1.:

133. H NMR (00013) 8 0.88 (d, g = 8 Hz, 3 H), 2.23
(s, 6 H), 2.33 (s, 3 H), 2.“0 (s, 3 H), 3.“3 (d, g = 8,
2 Hz, 1 H), “.93 (d, g = 2 Hz, 1 H), 5.20 (d, g = 2 Hz,
1 H), 6.86 (s, 2 H), 7.00 (s, 2 H); mass spectrum, m/e
(relative intensity) 262 (trace), 220 (35), 205 (100),
185 (10); with chemical ionization, (M + 1)+ = 263.

Ana1. Calcd. for C H C, 91.55; H, 8.“5.

20 22‘
Found: C, 91.56; H, 8.“9.
In a procedure similar to that described above,
when 100 mg of 132 was treated with HCl in 50 mL of
ethanol at reflux (2 h), GLC analysis of the crude

reaction mixture showed 2“% of 132 remained unreacted

and 76% of 133 was formed.
’L’L’L

56. 6,13-Dimetny1-5,7,12,18-tetrapheny1—5,6,12,18—tetra-

hydropentacene-5,1“;7,12-bis-endoxide 139 (R==CH3)

A solution of 25 (2.11 g, 5 mmol) and 1“8 (2.7 g,
”UL ’b’b’b

10 mmol) in 200 mL of anhydrous toluene was cooled to

 

 

H—
I

135

-78°C under argon (most of the 22 precipitated out). To
this suspension n-butyllithiwm(l2 mmo1)in SOIMLOf hexane
was added dropwise over a 2 n period. After the reaction
mixture was stirred for an additional 2 h at -78°C, it

was allowed to warm to room temperature. Methanol (1 mL)
was added. Toluene was removed on a rotary evaporator,

the remaining solid was di3501Ved in methylene chlor—

ide (100 mL) and was washed with water, dried (MgSOu)

and evaporated under vacuum. The remaining residue was
triturated with methanol (50 mL) and filtered to give

0.7 g (22%) of one pure isomer of 159 (R = CH3); mp above
360°C; 1H NMR (00013) 8 1.80 (s, 6 H), 6.73-7.83 (m, 28 H);
130 NH? (00013) 17.83, 91.67, 122.01, 128.65, 126.86,
128.80, 128.59, 129.01, 129.63, 129.63, 138.95, 150.31,
150.53, 150.92; mass spectrum, m/e (relative intensity)
682 (11), 537 (21), 832 (82), 380 (15), 105 (100). High

resolution mass spectrum: Calcd. for C“8H3“O2:

6“2.2617; Found: 6“2.2607.

The remaining solid from concentration of the metha-
nol solution was chromatographed on silica gel. Elution
with hexane removed 0.56 g of unreacted 138. Further
elution with 3:1 hexane:methylene chloride removed 1.06 g
(33%) of 139 (R = CH3) as a mixture of two isomers

(total yield 67% based on consumed diphenylisobenzofuran).

 

 

 

136

57. 6,13-Dimethoxy—5,7,12,1“-tetraphenyl-5,6,12,l“—tetra-
)

 

hydropentacene-5,1“;7,12-bis-endoxide 139 (R = OCH3
‘h'b

 

 

In a procedure similar to that used for l“9 (R = CH3),
'L’b’b

reaction of 92 (2.27 g, 5 mmol) and 129 (2.70 g, 10 mmol)
’b’b ’b’l/b

in 200 mL of anhydrous toluene with n—butyllithium (12

mmol) at -78°C gave a crude product mixture. Trituration

of this crude mixture with 50 mL of hexane and filtration

gave 1.85 g of a yellow solid which was chromatographed
on silica gel. Elution with hexane removed 0.“5 g of
unrea ‘

cteo 1,3-diphenylisobenzofuran 158. Further
eluticn with 3:1 hexane:methylene chloride first resulted

in 1.02 g (30%) of 18% (H = OCH ) as a mixture of
'rb

3
isomers. The second fraction (0.38 g, 12%) was a pure
1 1 .r
isomer of 1“9, mp 355—357°C; H NMH (CDCl ) 6 2.66 (s,
mm) ‘ 3
1 ’2
.J

6 H), 6.9—8.0 (m,

(\J

8 H); c NMR (00013) 8 60.93, 91.37,
121.68, 125.68, 128.05, 128.38, 128.61, 129.18, 129.39,
13“.3“, 1““.22, 1“5.“1, 150.91; mass spectrum chemical
ionization (H+ + 1) = 676, (M+ + 29) = 703. High resolu—
tion mass spectrum: Calcd. for C 03(M+-C H50):

“1H29 7

569.21167; Found: 569.205“5.

58. 9,10-Dimethyl-l,“,5,8-tetrapheny1-1,“J5,8-tetrahydro-

 

anthracene-l,“;5,8-bis-endoxide 150 (R = CH3)
mmm——“-’”"

 

In a procedure similar to that used for 132, reaction

of 25 (2.11 g, 5 mmol) and 1“7 (2.2 g, 10 mmol) in 100 mL
"\I’b 'b’b’b

 

 

L

137

of anhydrous toluene with n-butyllithium (12 mmol) at 0°C
gave a crude product mixture. Trituration of this crude

mixture with methanol (20 mL) gave 0.83 g (16%) of a pure

isomer of 150 (H = CH ), mp 320-321°C (dec.); 1H NMR
mm. 3
(C001,) 6 1 03 (s, 6 H), 7.16 (s, “ H), 7.17—7.66 (m,
'2
20 H), 140 NMR (00013) 8 18.67, 98.29, 128.10, 127.96,

128.29, 128.53, 137.13, 188.87, 150.66; mass spectrum,
m/g (relative intensity) 582 (trace), 527 (trace), “37
(2), 105 (100), 77 (12). High resolution mass spectrum:

Calcd. for C 5“2.22“5; Found: 5“2.22“7.

80H3002‘
The remaining solid from concentration of the metha—
nol solution was chromatographed on activated alumina.
Elution with “:1 hexane:methylene chloride first removed
0.85 g of unreacted 187. The second fraction gave 0.69g

’L’L’L

(25%) of 150 (R = CH3) as a mixture of two isomers, (total
'v’b’b

yield 52% based on consumed 2,5-dipheny1furan).

59. 9,10-Dimethoxy-1,“,5,8-tetraphenyl—1,“,5,8-tetrahydro—

 

 

anthracene-1,“;5,8-bis—endoxide 150 (R = 0CH3)
'U

In a procedure similar to that used for l“9, reaction
’V'Vb

of 92 (2.77 g, 5 mmol) and l“7 (2.20 g, 10 mmol) in 250 mL
'b'b

’b'b'b
of anhydrous toluene at 0°C with n-butyllithium (12 mmol)

gave a mixture of crude products. Trituration of this
crude mixture with hexane (50 mL) and filtration gave
0.16 g (6%) of a pure isomer of 150 (R = 0CH3); mp 303-

1

305°C (dec.); H NMR (00013) 8 1.96 (s, 6 H), 7.0-7.6 (m,

 

 

138

m

2 H); mass spectrum, m/e (relative intensity) 57“(trace),

“69 (“2), ““3 (1“), 36“ (8), 105 (100). High resolution

mass spectrum: Calcd. for C 03(M+ - H50):

33H25 C7

“69.18037; Found: “69.17839.

The remaining solid from concentration of the hexane
solution was chromatographed on activated alumina. Elution
with 95:5 hexane:chloroform first removed 1.56 g of
unreacted diphenylfuran 137. The second fraction
resulted in 0.156 g (9%) of mono—adduct 151, mp l82-l8“°C;
*H NMR (0301 ) 8 3.33 (s, 6 H), 6.80 (s, 2 H), 7.03-7.66
(m, 12 H); mass spectrum, m/e (relative intensity) 356
(13), 339 (13), 307 (8), 299 (9), 251 (100), 165 (13),

189 (33), 105 (78). High resolution mass spectrum:

Calcd. for C2UH2003: 356.1“125; Found: 356.13757.

Further elution with 50:50 hexanezchloroform gave
0.365 g (13%) of a mixture of two bis-adduct isomers (50%

total yield of bis-adducts based on diphenylfuran used.)

60. 6,7,1“,15-Tetramethyl-5,8,13,16-tetrapheny1—5,8,13-

16-tetrahydrohexacene-5,16;8,l3-bis-endoxide 152

'U

In a procedure similar to that used for 1“9, reaction
'b'b’l;
of 9“ (2.5 g, 5 mmol) and 188 (2.7 g, 10 mmol) in 200 mL of
'V'b 'b’b’b
anhydrous toluene with n-butyllithium (12 mmol) gave a

yellow solid which was chromatographed on silica gel.

 

 

 

139

Elution with hexane removed a trace of unreacted 189.
’L'L’b

Further elution with 3:1 hexane:ch1oroform gave as the

first fraction 1.23 g (38%) of a pure isomer of 152;
’b’b’b
1

mp 357-358°c; H NMR (CDC13) 8 2.13 (s, 12 H), 6.9-7.8
(m, 28 H); 13C NMR (CDC13) 8 22.97, 92.29, 121.63,
125.98, 127.67, 127.95, 128.78, 129.01, 129.69, 135.21,

189.83, 189.66 (two peaks are missing, possibly over-

178

lapped); mass spectrum, m/e (relative intensity) 720 (3),
615 (8), 600 (2), 510 (5), 105 (100), 77 (23). High

resolution mass spectrum: Calcd. for CS8H86O2:

 

if.

720.3028“; Found: 720.30082.
The second fraction gave 1.73 g (“8%) of 152 as a
'b’V'b

mixture of two isomers.

61. Reaction of 189 (R = CH3) with n—butyllithium in
fiU

 

the presence of ferric chloride

To a suspension of anhydrous ferric chloride (0.“87gg
3 mmol) in 25 mL of anhydrous THF at -78°C under argon,
was added dropwise n—butyllithium (9 mmol). The reaction
mixture was kept at -78°C for 2 h. To this suspension
was added dropwise a solution of bis-adduct 189 (R = CH3)
(0.682 g, 1 mmol) in 25 mL of anhydrous THF. Later the
reaction mixture was allowed to warm to room temperature
and filtered. 50 mL of ether and 10 mL of water were
added to the filtrate. The organic layer was separated,
dried (MgSOu) and concentrated to give 0.68 g (100%) of

the unreacted starting material 189 (R = CH ).
WWW 3

 

180

 

62. Reaction of 189 (R = CH3) with Zinc in Acetic AcidJ

’L’b’b
8,8,2

A suspension of bis—adduct 189 (R = CH ) (200 mg)
'Vbq, 3
and zinc dust (8 g) in 100 mL of glacial acetic acid was
heated at reflux for 6 h. After cooling the reaction

mixture to room temperature the solvent was removed

 

I."
(rotovap) and the organic product was taken up in 100 mL ‘
of chloroform. The chloroform solution was washed with
water and dried (MgSOu). Concentration of the chloroform ‘
gave 190 mg (100%) of 158. This compound starts to l

sublime at about 280°C and finally melts at 270-272°C

upon rapid heating. 1H NMR (CDCL3) 6 “.86 (s, 8 H),
7.0-7.“0 (m, 28 H); mass spectrum, m/g (relative intensity)
608 (80), 571 (15), 265 (57), 257 (52), 226 (58), 91

(37), 83 (100). High resolution mass spectrum: Calcd.

for C88H32: 608.25081; Found: 608.2“766.

63. Reaction of 189 (R = 0CH3) with Zinc in Acetic
W’b'b

 

Acid (155)
“WWW—

A suspension of $89] (R = 0CH3) (100 mg) and zinc dust
(2 g) in 80 mL of glacial acetic acid was heated at reflux
under argon and intflmadark. After 2 h the reaction mixture
was cooled to room temperature and 50 mL of oxygen~free
water was added to the solution. A greenish—blue solid
which formed was filtered under argon and washed with

oxygen—free water to give 80 mg (88%) of the crude

181

pentacene 152, which melts at 285-290°C upon rapid
heating; 1H NMR (CDC13) 8 3.61 (s, 6 H), 6.90-7.30

(m, 28 H); mass spectrum, m/e (relative intensity) 682
(3), 588 (30), 303 (16), 291 (37), 253 (100), 21“ (31)-
High resolution mass spectrum: Calcd. for C88H3802:

682.25589; Found 682.25892.

6“. Reaction of 25 with n-butyllithium in the presence

 

In a procedure similar to that used for 2%, reaction
'b

of (“.22 g, 10 mmol) with 155 (n = 3) (2.3 g, 10 mmol)

5
'"u 'Vb’b
50 mL of dry toluene and 12 mmol of n-butyllithium at

(7 M)

Y‘

11

Ho
5...;

—78°C gave “.75 g of a yellow residue which was chromato-
graphed on activated alumina. Elution with hexane first
removed 0.175 g of unreacted 25 and 0.67 g of unreacted
155 (n = 3). Further elution with 8:1 hexanezethyl
acetate gave as the first fraction, 2.88 g (51%) of 1:1

1

adduct 157 (n = 3), mp 158-159°C;
mmm

(s, 6 H), 2.10-2.15 (m, 2 H), 2.13 (s, 6 H), 2.83 (s,

H NMR (CD013) 6 1.73

6 H), 3.83-3.76 (m, 8 H), 5.63 (s, 2 H), 6.50 (s, 2 H);
13c NMR (00013) 6 12.87, 18.88, 20.63, 32.86, 32.86,
(overlap), 82.07, 82.51, 77.37, 105.13, 126.25, 127.11,
132.88, 187.82, 150.26; mass spectrum, m/g (relative
intensity) 892 (1.5), 150 (66), 189 (95), 120 (37), 108
(100), 95 (36). High resolution mass spectrum:

Calcd. for C23H28Br2N2: “92.06006; Found: “92.05920.

 

 

182
The second fraction gave 1.003 g (21%) of 2:1 adduct

158 (n = 3), mp 122-125°C (gas evolved); 1H NMR (CDCl ) 6
xxx 3

1.73 (s, 12 H), 2.80 (s, 12 H), 1.73-280 (m, 6 H), 6.50

(s, 8 H); 13C NMR (CDC13) 8 18.59, 20.61, 33.06, 83.89,
77.35, 126.70, 132.33, 187.68, 150.29; mass spectrum,

m/g (relative intensity) 75“ (M+, trace), 388 (8),3“2 0%)),
153 (18), 97 (27), 98 (100), 70 (85).

Anal. Calcd. for C31H3uBruN2: C, “9.39; H, “.5“;.N,3.7l;

Found: C, 89.50; H, 8.53; N, 3.75.

0
U1
‘11

(6

 

; action of 25 with n—butyllithium in the presence
"b'b

of dipyrrole 155 (n = 8)
’b’b'b—w

 

In a procedure similar to that used for 29, reaction

of 25 (“.22 g, 10 mmol) with 155 (n = 8) (2.8“ g, 10 mmol)
91% ’b'b’b
in 150 mL of dry toluene and 12 mmol of n—butyllithium at

-78°C gave “.77 g ofzacrude product mixture which was
chromatographed on activated alumina. Hexane first

eluted 0.65 g of unreacted dipyrrole 155 (n = 8). Further
elution with “:1 hexane:ethy1 acetate, gave as the first
fraction 0.667 g (15%) of 1:1 adduct of 127 (n = 8),

as a viscous oil; 1H NMR (CDC13) 8 1.30-1.66 (m, 8 H),
1.76 (s, 6 H), 2.13 (s, 6 H), 2.80 (s, 6 H), 3.36-3.66

(m: 8 H), 5.56 (s, 2 H), 6,50 (s, 2 H); 13

C NMR (CDC13)

8 12.57, 18.89, 20.66, 29.00, 30.28, 83.52, 85.17, 77.81,
105.18, 126.33, 127.23, 132.39, 187.61, 150.33; mass
spectrum, m/g (relative intensity) 506 (5), 163 (“2),

150 (100), 120 (33), 108 (98), 98 (56). High resolution
mass spectrum: Calcd. for 028H3oBr2N2: 506.07572; Found:

506.07153.

 

 

 

183

The second fraction gave 2.2“ g (“7%) of 2:1 adduct
1

 

158 (n = 8), mp 218-219°C;
"VL'L

8 H), 1.76 (s, 12 H), 1.90-2.33 (m, 8 H), 2.80 (s, 12 H),

H NMR (CDC13) 8 1.50-1.66 (m,

6.53 (s, 8 H); 13C NMR (001“, CD3CN) 6 18.26, 20.51,

29.63, 88.89, 77,30, 125.67, 131.95, 187.30, 151.20; mass
spectrum, m/e (relative intensity) 768 (M+, trace) %%9(35),
388 (15), 382 (100), 262 (12), 236 (16), 70 (21),

).

Anal. Calcd. for C32H36BruN2: C, 50.03, H, 8.72;N, 3.65;

(\3

82 (8

Found: C, 89.91; H, “.72; N, 3.65.

 

66. Reaction of25 and n-butyllithium in the presence

 

’11
of dipyrrole 155 ( n = 5)
'L'L’L

 

 

In a procedure similar to that used for 29, reaction
'L'b
of 25 (“.22 g, 10 mmol) with 155 (n = 5) (2.58 g, 10 mmol)
(Nu/i, ’b
in 150 mL of dry toluene with 12 mmol of n-butyllithium
at -78°C gave 5.37 g of a crude product mixture which
was chromatographed on activated alumina. Hexane first
eluted 0.“ g of unreacted 25 and 1.72 g of unreacted
'L

155 (n = 5). Further elution with 8:1 hexane:ethyl
'b’b'b

acetate, gave as the first fraction 0.86 g (16%) of 1:1

adduct 157 (n = 5), mp 106-107°C; l
mmm

H NMR (CDC13) 8 1.03-
1.66 (m, 6 H), 1.76 (s, 6 H), 2.16 (s, 6 H), 2.86 (s,

6 H), 3.83-3.83 (m, 8 H), 5.65 (s, 2 H), 6.53 (s, 2 H);
13C NMR (CDC13) 8 12.87, 18.81, 20.60, 25.29, 30 91,

31.58, “3.89, 85.30, 77.39, 105.05, 126.21, 127.13, 132.30,

188

187.5“, 150.39; mass spectrum, m/e (relative intensity)
520 (7), 382 (2), 178 (21), 168 (100), 108 (63). High
resolution mass spectrum: Calcd. for C25H32Br2N2:

; Found:

The second fraction gave 2.20 g (81%) of 2:1 adduct

58 (n = 5), mp BBQ-231°C; l

H NMR (00013) 8 1.0-1 60 (m,
H), 1.76 (s, 12 H), 1.76-2.16 (m, 8 H), 2.83 (s, 12 H),
.50 (s, 8 H); ‘C HHH CCC13) 8 18.82, 20.62, 26.09,
31.71, 85.37, 77.80, 126.18, 132.28, 187.57, 150.88;

,1 . , . . . ' +
mass spectrum, m/e (relative 1ntens1ty) 782(NI, trace)

3&8 (9), 370 (5), 382 (30), 165 (12), 97 (28). 98 (100)

.ErhN : C, 50.66; H, 8.90; N, 3.58;

 

Found: C, 50.57, H, 8.99; N, 3.61.

67. Reaction of 25 with dipyrrole 155 (n = 5) and n—
'u% ’VVL

butyllithium (attempted synthesis of 156)
www-

 

 

 

A solution of 25 (“.22 g, 10 mmol) and 155 (n = 5)
"0% ”MW/b

(2.58 g, 10 mmol) in 250 mL of dry toluene was cooled to
-78°C under argon (most of the 25 precipitated out). To
this suspension n-butyllithium (22 mmol) in 100 mL of
hexane was added dropwise over 8 h. The reaction mixture
was allowedtx>gradually warmtxiroom temperature. Methanol
was added (1 mL) and the toluene solution was washed with
water and dried (MgSOu). Concentration of the solvent

gave 3.7 g of a yellow solid. Careful column chromato-

graphy of this solid on activated alumina failed to

 

 

185

give any basket-type compound 156. The product had a
broad band on TLC, did not melt below 300°C and did not

show any conclusive NMR or mass spectral data.

68. Reaction of 157 (n = 5) and butyllithium (attempted
‘U

 

 

synthesis of 156)
’L’L’L—

 

Solutions of 157 (n = 5) (0.8 g, 1.5 mmol) in
’b’b’b
100 mL of dry toluene and of n-butyllithium (3 mmol)
in 100 mL of hexane were added dropwise simultaneously
at the same rate to 250 mL of dry toluene at —78°C under

argon over a period of 8 h. The reaction mixture was

 

allowed to gradually warm to room temperature. After
work-up 0.6 g of a viscous oil remained. Column chromato-
graphy of this oil on activated alumina did not give any
156; rather, some butylated product along with polymeric

material was obtained.

 

PART II

METALLACYCLOPENTANES AS CATALYSTS FOR THE

LINEAR AND CYCLODIMERIZATION OF OLEFINS

186

_ RIPE-Q ' .

 

em;

 

187

INTRODUCTION

Conflicting explanations have been advanced to account
for the observation that certain transition metals cata-
lyze reactions which are thermally "forbidden" by the
Woodward-Hoffman conservation of orbital symmetry rules}09
e.g., as in the [2+2] cycloaddition of alkenes to form a
cyclobutanenxfltfigror the corresponding cycloreversion
reactions. 0n the one hand it has been proposed that the

new C-C bonds are formed simultaneously,110 (eq. 1) and

..__... . .. t...)

that the function of the metal is to act merely as a tem-

plate111 which provides d orbitals of suitable symmetry

r--fi
:M:

find

 

 

Hill ===

 

This part of my research was done under the supervision
of Professor R. Grubbs while he was at Michigan State
University. My contribution to this subject, combined
with that of others under Dr. Grubb's supervision, led
to a communication to the Editor, J. Am. Chem. Soc.,
100 7816 (1978) which failed to mention my name. In

is part I will try to explicitly describe my contri—
bution and also mention other authors' work in order to
present the wide scope of this subject.

 

 

 

188

to mix with the orbitals of the organic species, thereby

rendering the reaction symmetry "allowed."112 An alterna-

113 is a nonconcerted mechanism

tive interpretation
involving the stepwise formation of an M—carbon o—bonded
intermediate followed by reductive elimination of the

hydrocarbon, as shown in eq. 2.

“Mn“ :1” l ) 2 + M (ea-2)
M

Such intermediates have been implicated in catalytic
113a

 

 

1'.—

valence iso-
113b

processes involving olefin metathesis,

merization of cubane to syn-tricyclooctadienes, and

cycloaddition reactions of norbornadienes.llu Osborn

115

et al. reported the isolation of a stable metallacycle

129 from the dimerization of norbornadiene.
’b

k

I + [Ir(1.s-coo)CI] ____. I h

/ ‘6
N80 CI N80

159

Since then a variety of metallocycles have been

116 117

prepared. Grubbs and coworkers reported in 1977

189

the preparation and reactions of a series of phosphine
nickelacyclopentanes (162)7Hflxfl1undergo a competitive
B-carbon cleavage, the reverse of the first step of the
[2+2] cycloaddition reaction, reductive elimination,
the required second step of the [2+2] cycloaddition
reaction, and B-hydride transfer, the normal

reaction of metal alkyl complexes.118

 

 

Nip: . CH1=CH2+ D + I—butcne

 

1620

The complexes were prepared by addition of 1,8-dillithio-

119

butane (161) to the appropriate dichlorobisphosphine-

’Vbq,
nickel (II) complex (160) in ether at -78°C. The temper-
ature was slowly raised to -20°C and the resulting yellow

solid formed at this temperature was isolated by filtra—

 

 

tion.
other
9,880, + Li-(CH,)‘-I.i _> Ni P,
-78°c
160 161 162 6,6,.)

150

When a toluene solution of 162 was treated with an
W’b’b

excess of Ph3P at -10°C, the bright yellow solution gave

1

golden crystals of 168a. H NMR and 31? NMR spectra

mmmm
and the molecular weight information were consistent
with the following equilibration for the phosphine com-

plexes (Scheme 10).

 

 

Scheme 10
P
[:::>qip + p ‘12:::::=;- 3'3 .:=:::==7' [qua Ln
1630-C 1620-C 164 a—c

l
p C] C"

These phosphine-nickelacyclopentanes decomposed by

"II
n
.2

reductive elimination, B-hydride elimination, or C-C
bond.cleavagedepending on the coordination number of
the complex (see Scheme 10).

Grubbs and coworkers120 designed a deuterium labeling

experiment in order to determine the relationship between

 

151

metallacyclopentanes and bis-(olefin)—metal complexes.
Their results suggest that there is an equilibrium
between bis (olefin) complexes (165) and metallacyclo-

pentanes and this may be a key reaction in a number of

 

metal-catalyzed reactions of olefins.

 

 

Ni(Ph,P)3 ‘* :> ”1,? + (”139): Ni

164 165

 

Metallacyclopentanes were then tested.as a catalyst.
Our approach was to react different olefins with

tris(triphenylphosphine)nickel complex 168%. The reaction

 

 

 

 

152

product is expected to be bis (olefin) complex 166 in
’VVM

equilibrium with disubstituted metallacyclopentane 167
'VVD

which upon oxygen decomposition would produce disubsti-

 

tuted cyclobutanes (168).
WWW
Disubstituted cyclobutanes are commercially important
materials. We expected to synthesize a variety of these
disubstituted cyclobutanes by using cyclodimerization :-
of the corresponding olefins and metallocycles as

catalysts.

 

 

153

RESULTS AND DISCUSSION

In an experiment designed to cyclodimerize acrylo—
nitrile in the presence of tris(triphenylphosphine)
tetramethylene Ni(II) 168a as catalyst, a solution of

N'D'b’b

168a in acrylonitrile at -20°C under argon was kept for
'b'b'b'b

0.5 h; a bright yellow solid came out of solution. The

 

reaction mixture was gradually warmed to room temperature.
Introduction of pure oxygen to this solution at -78°C

quickly destroyed the yellow complex. The resulting

 

dark brown oil left after removal of the excess acrylo- L,
nitrile was analyzed by 00. This crude reaction product

contained a “8% yield of 1,2-dicyanocyclobutane (168)

(calculated from amount of the 168% initially used).

The yellow precipitate in this reaction is presumably

the dicyano substituted metallacycle 167 (R = CN),

but it was not characterized.

Although this cyclodimerization was not catalytic,

 

it showed that cyclodimerization is possible, and that
more study is needed in order to find the right conditions
to make the reaction catalytic.

In a similar reaction, bis(triphenylphosphine)
tetramethylene Ni(II) (162a) was also used as a catalyst
for cyclodimerization of acrylonitrile. Only an 8%
yield of 1,2—dicyanocyclobutane was obtained. Thus 168%

is a more reactive catalyst than 162a.
’Vb’h’b

158

 

Ni(PPh3)3 . '=\ ‘5”

CN (cw),

164a

Ni (P ”13);“ a

167(R=CN)

)

1

 

4856

Ch!

loans-cw)

Chi

Grubbs and coworkers121 successfully used 168a in

the catalytic dimerization of ethylene.

’b'b’b
In order for

the reaction to be catalytic in nickel, the ethylene

122

complex of nickel must revert to metallacycles

O 2C2W

under ethylene pressure. Consequently, nickel-phosphine

complexes of ethylene were examined.

It was found that

the reaction of bis(triphenylphosphine)ethylenenickel

(0) 169 (-10°C, 72 h), with 80 psi of ethylene produced

WWW

a 25% isolated yield of the metallacycle 162a. Cyclo-
Wmmm

butane (20%) and 1-butene were also produced in this

reaction.

 

 

155

80 Psi

(8%,)2 Ni ((28%) + c214, -lo°c—> Ni(PPh,);D+I/\

169

 

1620

As a result, when 168a was dissolved in toluene and
’VL’VD
treated with ethylene (80 psi), cyclobutane and butenes
were formed. The product ratio depended upon different
factors (i.e. temperature, solvent and concentration of
the catalyst). Solvents such as toluene resulted in
the production of cyclobutane while chlorobenzene produced

a very active catalyst for the linear dimerization of

ethylene to l-butene.

Propylene and 1,7—octadiene were also cyclodimerized

using 168% as a catalyst. This catalyst did not require
an aluminum alkyl cocatalyst as do the more standard

nickel oligomerization catalysts.123

 

 

 

 

156
1) 1640
013— CH = CH, 9, o o 2 -hexene
2) o,
48% 2%

 

__ I) 1646
__ _)- .
2) o, ‘
191.

Conclusion: This work, combined with that of
others, demonstrates that metallacycles can play a major

role in the dimerization of olefins to produce products

normally not obtained by the usual metal hydride catalysts.

 

 

 

157

EXPERIMENTAL

l. Bis(triphenylphosphine)nickel (II) dichloride (1603)
—'\J’\;’V\:—

This compound was prepared according to the literature
methodzl2u a solution of triphenylphoSphine (52.6 g,
0.201 mol) in 500 mL of glacial acetic acid was heated
on steam bath in a one—liter r.b. flask under argon
until all the PPh3 was dissolved. In another flask
NiCl2, 6H2O (23.8 g, 0.1 mol) and 80 mL of water were
stirred until most of NiCl2 was dissolved, then 250 mL
of glacial acetic acid was added and the mixture was
heated on the steam bath. Both solutions were degassed
by bubbling argon through while they were warm.

The NiCl solution was added to PPh3 solution while

2
it was stirring on a steam bath. A blue-green micro-
crystalline precipitate immediately formed. The steam
was turned off andtfluereaction mixture was stirred under
argon at room temperature for 10 h. The blue crystals
were filtered under vacuum and washed with acetic acid

(2 X 10 mL) and then dried under vacuum for 20 h to give

“8.6 g (78%) of 160a.
WWW/X;

2. 1,8-dilithiobutane (161)
mmm

 

This compound was prepared according to the litera-

125

ture as follows: in a 500-mL 3—necked flask equipped

with an argon line and a 250-mL addition funnel, were put

158

5 g (excess) of cut—up lithium ribbon and 200 mL of

dry ether. To this suspension at 0°C a solution of
1,8-dibromobutane (81 g, 0.19 mol) in 100 mL of dry
ether was added dropwise over 3 h. After 0.5 h
additional stirring, the solution was stored in the
refrigerator overnight. A bluish-gray solid (LiBr)
settled out, which was separated by filtration under
argon. The concentration of 1,8-dilithiobutane in the
ethereal solution was determined by reaction of 10 mL

of this solution with trimethylsilyl chloride (2 mL)
under argon. The concentration of the resulting
l,8-bis(trimethylsilyl)butane in solution was determined
by GLC (5% DC-550 on chromosorb G; 6', k", 95°C) using
durene as an internal standard. Thus a concentration of
0.185 molar with respect to 1,8-dilithiobutane 161 was

obtained.

3. Bis(triphenylphosphine)tetramethylenenickel (II)

(162a)

.m’b'b’b-

This compound was prepared according to Grubbs et a1.

as follows:117

An ether solution of 1,8—dilithiobutane
(161) (63 mL, 12.8 mmol) was added slowly to a suspension
of bis(triphenylphosphine)dichloride (II) (162) (5 g,

7.5 mmol) in 100 mL of ether. The mixture was maintained
at —50°C during the addition and then slowly warmed to
0°C. A bright yellow solid appeared at -lO°C to 0°C

and was collected by filtration (-10°C). The yellow

159

solid was dissolved in oxygen—free toluene and filtered
(at -15°C) to remove lithium chloride and starting
material. After partial concentration (-15°C) of the
toluene solution, hexane was added. Bright yellow
crystals (1.73 g, 36% yield) of 162a were formed over-
night at dry ice temperature. Amgggtion of the complex
was decomposed with sulfuric acid at —30°C. A 98%
yield of n-butane, which is characteristic of this
complex, was produced. fflueanalysis was done by GLC

on a Varian series 1800 instrument equipped with a

flame ionization detector, using a Duropak (20 ft)

paraffin wax-5% AgNO3 on A1203 (13 ft) column.

8. Tris(triphenylphosphine)tetramethylene Ni(II)
68a)

(1
—mmmm—

 

This compound was prepared according to Grubbs et

611.117

as follows: an ethereal solution of 1,“—
dilithiobutane (161), 6.88 mmol, was added slowly to a
suspension of bis(triphenylphosphine)dichloride Ni(II)
(1602) (3 g, 8.58 mmol), in 90 mL of dry ether at -60°C
under purified argon. Thenuxture was kept at -60°C

for 0.5 h, then slowly warmed. At -30°C a yellow solid
appeared which disappeared to give a clear brown solu-
tion when the reaction mixture was warmed to 0°C. This
solution was cooled to -10°C and 6 g of triphenylphos-
phine was added. The color of the solution quickly

turned deep brown and a gold-brown solid precipitated.

 

 

160

This solution was stirred for 6 h at 5°C to 0°C and

then the solid was filtered under argon. For purification
the solid was taken up in 20 mL of oxygen-free toluene

at —30°C, warmed to zero degrees and filtered (168a is
soluble in toluene whereas lithium halides are not).

The toluene solution was stored in a dry ice box over-
night and the gold-brown solid was filtered to give

1.7 g (51%) of a pure sample of 168%. A small sample of
1683 was decomposed with H280“ under argon at room
temperature. A mixture of ethylene, l-butene and 2—butene
and cyclobutane, which is characteristic of this

complex, was formed. The mixture of gases was analyzed
by gas chromatography on a Varian series 1800 instrument
equipped with flame ionization detectors, using a

Duropak (20 ft) and a paraffin wax -5% AgNO3 on

A1203 (13 ft) column.

5. Cyclodimerization of acrylonitrile

 

A solution of 168a (0.928 g) in acrylonitrile
'b’b’b’b

(5 mL) at -20°C under argon was kept for 0.5 h; a bright
yellow solid came out. The reaction mixture was gradually
warmed to zero degrees (some of the complex decomposed),
then it was left to warm to room temperature and kept for
6 h. The flask was then cooled to -78°C, evacuated and
filled with 02. After connection to a bubbler, the

flask was warmed slowly to room temperature. The product

 

ififii.
"4

 

 

161

was purified by GLC (DC 550, 120°C) to give a “8% yield
of 1,2-dicyanocyclobutane lgg (R = CN) (durene was used
as an internal standard). The product was compared with
an authentic sample of cis- and trans-1,2—dicyanocyclo—
butane obtained from Aldrich Chemical Co. The proton
NMR spectrum showed peaks at 6 3.u5 (m, 2 H), and 2.UO
(broadened g of d, H H). The GLC trace was similar to

that of the commercial isomer mixture.

APPENDIXES

Appendix 1

Crystallographic Data for Compound 222
'b —

 

Crystals of 232, C20H22O2’ are monoclinic; space

group PEl/n; a = 9.697(5), b = 7.582(U), c = 11.185(6)fi,
B = lll.l7(b)°; Z = 2; M = 29U.39; pC = 1.275 g cm-3.
Lattice dimensions were determined using a Picker FACS-I

diffractometer and MoKdl (A = 0.70926A) radiation.

Intensity data were measured using MoKa radiation

(29 = 65°) yielding 2772 total unique data and, based

on I>2o(I), 2297 observed data. The data were reduced;126

the structures were solved by direct methodsgl‘;7 and the

refinement was by full—matrix least-squares techniques.128

max

The final R value was 0.0H8. The final difference
Fourier map showed densities ranging from +0.37 to

-0.30 with no indication of missing or incorrectly placed
atoms. Bond lengths and bond angles are givenijlthe

following pages.

162

 

 

 

 

 

.
a O 3
< ‘h d
“
u N

(:1)

cf

16U

Bond Distances (E) for 29b

U)

 

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165

'b’b'b

Bond Angles (°) for 29b.

an le

atoms

 

 

 

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000C):ECEFEfilmfiimtflifimtflffifflmfflQO

-C(1OM)
-C(10M)
-C(10M)
-C(1OM)
-C(1OM)
—C(1OM)
—C(1OM)
-C(1OM)
-C(1OK)
-C(1OM)
—C(1OM)
-C(1OM)
-C(10M)
-C(1OM)
—C(10M)
—C(1OM)
-C(10M)
—C(1OM)
-C(10M)
-C(2)

—C(2)

-C(3)

-C(3)

166

Bond Angles (°) for 29b Continued.
’b'b’b

—H(9A)
-H(7B)
-H(BB)
-H(9B)
-H(8A)
-H(9A)
-H<7B>
-H(BB)
—H(9B)
—H(9A)
-H(7B)
-H(8B)
-H(9B)
-H(7B)
-H(BB)
-H(9B)
-H(8B)
-H(9B)
-H(9B)
-H(10)
-H(10)
-H(11)
-H(ll)

109.
118.
115.
112.
106.
125.
13“.

73.

A6.

99.

133.
61.
A7.
51:.

138.
93.

105.

111.

122.

132.

130.

123.

 

OOOOOOOOOOOOOOOOOOOOOOO
AAAAAAAAAAAAAAAAAAAAAAA
l—‘l—‘F—‘F—‘tmw DWEWWEWWWEDEMNWM
vvvvvvvvvvvvvvvvvvvvvvv

 

167

Appendix 2

 

 

Crystallographic Data for Compound 86 (R = OCH3)
’b'b —

Crystals of 86 (R = OCHB), C36H26O2’ are mono-
clinic; space group P2l/c; a = 8.228(3), b = 18.797(9),
c = 16.919(8)A, 8 = 99.29(3)°; Z = A; M = 490.60;
pC = 1.262 g cm-B. Lattice dimensions were determined
using a Picker FACE-I diffractometer and 1402011
(A = 0.70926A) radiation.

Intensity data were measured using MoKa radiation
(28 = 50°) yielding 4569 total unique data and,

based on I>2o(I), 1965 observed data. The data were
126

reduced; the structures were solved by direct
methods;127 and the refinement was by full—matrix least-
squares techniques.128 The final R value was 0.055. The

final difference Fourier map showed densities ranging
from +.A6 to -.52 with no indication of missing or

incorrectly placed atoms.

 

168

25 2
OCH
24 2] 3 “a 3
l3 4
23 22 ‘2 l4 .0
/ L

 

15

IO OCH '6 I9

17

86 (R=oCH,)

169

Distances (A) for 86 (R = OCH )
mm 3

 

{designates an

—C(A2)
-C(A1Ua)
-C(A3)
—C(AL)
—C(AUa)
-C(A5)
-C(A1Ua)
-C(A5a)
-C(A16)
-C(A6)
-C(Al3a)
—C(A13a)'
-0(A27)
—c(A1u)
—C(Alua)
-C(A15)
-C(Al6)
-C(A20)
-C(A17)
-C(A18)
-C(A19)
-C(A20)
-C(A28)
-C(B2)
-C(Blua)
—C(B3)
-C(Bu)
-C(BUa)
-c(BS)
-C(Blua)
-C(B5a)
—C(B16)
-C(B6)
-C(Bl3a)

atom at 2—x,-y,-z

.52

.39

:39

U1
LA)

HFJFJHFJFJHFJFJHFJFJHFJFJHFJFJHFJFJHFJFJHFJFJHFJFJH+4FJH
uufi
uno

stance

LA)
0)
R)

UL)
\DNON

u; t»
~J «a
mflmlrhflonflfiCDQMWUJdewflerNChO%QU)txnnnhultthFHQOVQCfi

AAA/\AAAAAAAAAAAAAAAAAA/\AAAAAAAAAAA
mm O\O\\1'\J\I\O l-"\] (DONONNN O\O\O\O\O\O\£TO\\)1 O\O\O\O\O\O\\1\J O\\]

UULA)
(I)\O

 

 

 

170

Bond Distances (A) for 86 (R
’b’b

0)

g)

{ I’)

 

(h C\

\1 \O (“N (T\\fl \D 11' J:'-_L) \Jv

VVVVV\-/Vvv CD
v

m m m m m m m m (I1 m 'U (’11

(30000’0’7‘JC‘JOFD00
AAA/\AA/‘\/\/\/\/\f\
R) 1—1 1—4 l—J #4 1—1 L——1 p4 1.1 1.:

CL
(0
U)
1..)
(7}
m
rf‘
(D
(D
D)

f.)

-C(Bl3a)"

—0(B27)

I
0
A
U?
1..)

r—
v

('DC3KO OD\] O GNU"! I... _
vvvvvvvvm

I
00 (J) O (0 F) ('7 C) O
AAA/\AAAAA
00 [D U? (I? (I1 '11 U) on EU
TUR)F—JL—|L-—JF\)1—JL.JL_J

atom at

v

1—x,-y,l-z

OCHB) Continued.

distance
1.393(6)
1.377(5)
1.533(6)
1.519(6)
1.53A(6)
1.390(6)
1.38u(6)
1.369(7)
1.381(8)
1.366(8)
1.393(7)
1.U32(7)

 

 

Bond Angles (°) for 86 (R = OCH )
mm 3

171

 

atoms

C(A2) -C(Al) —C(A1Aa)
C(Al) -C(A2) -C(A3)
C(A2) -C(A3) -C(AA)
C(A3) —C(Au) -C(Aua)
C(Au) —C(Aua) -C(A5)
C(Au) -C(AUa) -C(A1ua)
C(AS) -C(Aua) -C(A1Aa)
C(Afia) —C(A5) -C(A5a)
C(Aua) —C(A5) -C(A16)
C(AEa) -C(A5) -C(A16)
C(AE) -C(A5a) -C(A6)
C(AS) -C(A5a) -C(Al3a)
C(A6) -C(A5a) -C(A13a)
C(ASa) —C(A6) -C(Al3a)'
C(A5a) -C(A6) —0(A27)
0(A27) -C(A6) —C(Al3a)'
C(ASa) -C(A13a) —C(A6)'
C(A5a) -C(Al3a) -C(AlA)
C(AlU) -C(Al3a) -C(A6)'
C(Al3a) -C(A1U) -C(A1ua)
C(Al3a) -C(A1u) —C(A15)
C(Alua) -C(A1u) -C(A15)
C(Al) -C(A1ua) -C(Aua)
C(Al) -C(A1Ua) —C(A1u)
C(Aba) -C(A1Ua) -C(A1A)
C(Alu) -C(A15) -C(A16)
C(AlU) -C(A15) -C(A20)
C(Al6) -C(A15) -C(A20)
C(A5) —C(A16) -C(A15)
C(A5) —C(A16) -C(A17)
C(A15) -C(A16) -C(A17)
C(A16) -C(A17) -C(A18)
C(Al7) -C(A18) -C(Al9)
C(Al8) -C(A19) -C(A20)
C(A15) -C(A20) -C(A19)
C(A6) -0(A27) -C(A28)

'designates an atom at 2—x,-6,-z

angle

119.
120.
120.
119.
126.
120.
112.
105.
106.
105.
126.
112.
120.
119.
120.
119.
120.
112.
126.
109.
106.
105.
120.
126.
113.
112.
127.
119.
113.
126.
119.
119.
120.
120.
120.
112.

NOLA) J:'.I:-\O\Ol\)\0 MK) O CDHKO ONKOCDOJECD-xl JrfU\0\OU‘I tthKOU'I O 0000
AAA/\AAAAAAAAAAAAA/\AAAAAAAAAAAAAAAAAA
kw O\U'1U'I~U1U'I .I:'.1:U1 .t't'UWUW thtttkfi .t-EUWUW tttrrrmwmmmm
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

 

i

 

172

Bond Angles (°) for 86 (R = 0CH3) Continued.
"b";

 

_ atoms angle

C(82) -C(Bl) -C(81ua) 118.2(8)
C(81) -C(82) -C(83) 120.A(6)
C(82) —C(83) -C(8u) 121.1(7)
C(83) -C(8u) —C(8Aa) 119.0(8)
C(BA) -C(8ua) -C(85) 126.9(6)
C(EU) -C(Bua) —C(81ua) 119.0(7)
C(85) -C(BUa) -C(81ua) 113.5(5)
C(8ua) -C(85) —C(85a) 106.0(u)
C(8ta) —C(85) -C(816) 105.2(0)
C(85a) —C(85 -C(816) 105.3(u)
C(85) -C(E5a) —C(86) 126.8(5)
C(85) -C(B5a) —C(Bl3a) 113.U(u)
C(86) -C(85a) -C(813a) 119.8(5)
c(85a) -C(86) -C(813a)" 119.2(5)
C(B5a) -C(B6) —O(B27) 120.6(u)
0(E27) —C(86) —C(Bl3a)" 120.2(u)
C(B5a) -C(Bl3a) -C(B6)" 121.0(5)
C(85a) —C(Bl a) -C(81u) 112.8(0)
C(BlU) —C(B13a) -C(86)" 126.2(5)
C(Bl3a) —C(81u) -C(81ua) 105.u(u)
C(813a) -C(81u) -C(B15) 105.9(u)
C(B1Aa) -C(BlA) —C(815) 105.6(A)
C(81) —C(81ua) -C(8ua) 121.5(6)
C(Bl) -C(81ua) -C(B1u) 125.u(6)
C(8ua) -C(81ua) —C(81u) 113.2(5)
C(81u) -C(815) -C(Bl6) 113.1(u)
C(Blu) —C(B15) —C(B20) 125.6(5)
C(816) —C(Bl5) -C(B20) 121.3(5)
C(B5) -C(Bl6) -C(Bl5) 112.9(50
C(85) —C(816) -C(B17) 126.5(5)
C(815) -C(Bl6) 4C(Bl7) 120.7(5)
C(816) -C(817) -C(Bl8) 118.3(6)
C(817) -C(818) —C(Bl9) 121.u(6)
C(818) -C(819) -C(B20) 121.2(6)
C(B15) -C(B20) —C(B19) 117.2(6)
C(86) -0(B27) -C(B28) 112.0(5)

"designates an atom at l-x,—y,1-z

 

 

— .
2.1"." mt'N-

 

10.

11.
l2.

13.

19.
15.

173

REFERENCES

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Gilman, H.; Morton Jr., J.w. Org. Reaction 195“,
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Hart, F.A. J. Chem. Soc. 1960, 332M.
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Friedman, L-S Legullo, F.M. J. Am. Chem. Soc. 1963,
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Wittig, 0.; Pohmer, L. Chem. Ber. 1956, 89, 133“.
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Wittig, 0.; Harle, H. Justus Liebigs Ann. Chem. 1929,
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mmmm -

Hennion, 0.F.; Anderson, J.0. J. Am. Chem. Soc.

1296, 68, U2“.
m mm ——

 

 

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33.

3M.

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ibid. 126;, §§.”””W3766.

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Chim. Acta 197“, 57, 383.
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mmmm ‘—

 

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53.
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This is also true for the mono-benzo analogs, such as
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UU36.

 

 

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61.

62.

63.

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65.

66.

67.

68.
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70.

71.

72.

73.

7U.

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Gassmann, P.; Valcho, J. J. Am. Chem. Soc. 9919,
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Ostermayer, E.; Fittig, R. Chem. Ber. 1872, i 933;

 

VGlaser, C. Chem. Ber. 9999, i, 982, mmmm

 

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__— mmmm -—

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I

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81.

82.

83.

8H.

85.

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Lai, C.Y. Ph.D. Dissertation, Michigan State
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1!"; '

 

92.

93.

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98.

99.

100.
101.

102.

103.

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’VVb

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m ’V’b’ —

 

 

 

 

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