- ..__A.M-W ..'..

_ CONCERMNG THE MECHANiSM OF
THE OXEDATIVE DECOMPOSITION
63F CYCLOBUTADiENESRON TRICARBONYL

Thesis for the Degree of Ph. D.
MECHIGAN STATE UNIVER$iTY
ROGER ALLEN GREY
1973

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L I B R A R1
Michigan State
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thesis entitled .
T3; file Oxidafa ve
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Cbncern.
Decemposl hon
1"" tGV’bonyl

presented by

has been accepted towards fulfillment
of the requirements for

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degree 111

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Major professor

Date 4/;3/733

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ABSTRACT

CONCERNING THE MECHANISM OF THE OXIDATIVE
DECOMPOSITION OF CYCLOBUTADIENEIRON TRICARBONYL

By
Roger Allen Grey

The oxidative decomposition of cyclobutadieneiron
tricarbonyl in the presence of dienophiles was studied in
order to obtain a definite answer to the question of whether
or not "free" cyclobutadiene is an intermediate in this
reaction.

An optically active cyclobutadieneiron tricarbonyl Qg,
of known optical purity was prepared. Decomposition in the
presence of a variety of dienophiles with ceric ammonium
nitrate gaVe totally racemic product. It was concluded from
this result that significant reaction does not occur from
an intermediate where the dienophile and cyclobutadiene are
coordinated to the iron and that ”free" cyclobutadiene is

indeed an intermediate in this reaction.

CONCERNING THE MECHANISM OF THE OXIDATIVE
DECOMPOSITION OF CYCLOBUTADIENEIRON TRICARBONYL

By

Roger Allen Grey

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY
Department of Chemistry

1973

”It.
.I)
'9' n)
I ;
Vfi

‘
“"1
J“ '\
."

To my wife Nancy and daughter Kimberly Ann
whose love and understanding

during this work is greatly appreciated

ii

ACKNOWLEDGMENTS

The author wishes to express his sincere gratitude to
Professor Robert H. Grubbs for his expert guidance, keen
insight, patience, confidence and optimism which have
contributed greatly to my development as a chemist.

The author wishes to thank the undergraduates who
have contributed their technical assistance in preparing
starting materials for this thesis research.

Financial assistance, in the form of teaching
assistantships provided by Department of Chemistry,
Michigan State University, and research assistantships
from a National Science Foundation Institutional Grant
administered by Michigan State University are gratefully
acknowledged.

I wish to express my sincere appreciation to my
parents for their interest and encouragement in my
educational development and financial support during my
undergraduate years.

Thanks go to my fellow graduate students and in

particular members of the "group" who are truly unique.

iii

TABLE OF CONTENTS

Page
INTRODUCTION. . . . . . . . . . . . . . . . . . . . . 1
RESULTS AND DISCUSSION. . . . . . . . . . . . . . . . 18

Synthesis of a Chiral Iron Complex . . . . . . . 18

Attempted Resolution of Chiral Iron Complexes. . 21
The Decomposition of the Chiral Iron Complex . . 33
Conclusion . . . . . . . . . . . . . . . . . . . 42
EXPERIMENTAL. . . . . . . . . . . . . . . . . . . ... 43
General Procedures . . . . . . . . . . . . . . . 43
l-Methoxy-Z-butyne QQ. . . . . . . . . . . . . . 44
Vinylene Carbonate 4S. . . . . . . . . . . . . . 44

1- -Methoxymethy1- 2-  methy1 cis- 3, 4- .carbonyldioxy-
cyclobutene QI. . . . . . 4S

1-Methoxymethy1-2-methylcyclobutadieneiron
Tricarbonyl Qg . . . . . . . . . . . . . . . . . 45

l-Chloromethyl-2-methylcyclobutadieneiron
Tricarbonyl QSQ. . . . . . . . . . . . . . . . . 46

1-Bromomethyl-Z-methy1cyclobutadieneiron
Tricarbonyl QSQ. . . . . . . . . . . . . . . . . 47

1-Methoxymethy1-2-methy1cyclobutadieneiron
Tricarbonyl Q; from ERR or QSQ . . . . . . . . . 47

1- (NN-Dimethy1amine)methyl- 2-methylcyclobuta
dieneiron Tricarbonyl Q2. . . 47

1-Methoxymethyl-2-methylcycylobutadieneiron
Tricarbonyl pg from Q2 . . . . . . . . . . . . . 48

iv

TABLE OF CONTENTS (Continued)
Page

Potassium (+)~a-Methoxy-a-trifluoromethyl-a-
phenylacetate. . . . . . . . . . . . . . . . . . 49

1-(+)-a-Methoxy-a-trifluoromethyl-a-pheny1-
acetoxymethyl-2-methy1cyclobutadieneiron
Tricarbonyl Zfi . . . . . . . . . . . . . . . . . 49

2, 2, 3, 3- Tetracyano- S- methoxymethyl- 6- -methyl-
bicyclo[2. 2. .0]hex- 5- ene 12. and Isomers fifi, fifi
and fifi. . . SO

3- Methoxymethyl- 4- -methyl- 8- azatricyclo-
[4.3. 0.02 5]nona- 3- ene- 7, 9- dione- 8- -pheny1 .fi4
and Isomers fifi, fifi and fiz. . . $1

3- Methoxymethyl- 4- -methyltricyclo[4. 4. 0. 02 5]-
deca- 3, 8- diene- 7, 10- dione fig and Isomers 2Q,

fifi and fifi. . . . . 51
Resolution of 1-(NN-Dimethylamine)methyl-Z-
methylcyclobutadieneiron Tricarbonyl fifi. . . . . 52

Nmr Experiments with the Trapped Adducts and
Eu(hfbc)3. . . . . . . . . . . . . . . . . . S3

Decomposition of Optically Active 1-Methoxy-
methyl-2-methylcyclobutadieneiron Tricarbonyl

fig with Zfi, fifi and fifi. . . . . . . . . . . . . . 54

BIBLIOGRAPHY. . . . . . . . . . . . . . . . . . . . . 55
APPENDIX. . . . . . . . . . . . . . . . . . . . . . . S7

TABLE

LIST OF TABLES

Mass Spectrum of 3- Methoxymethyl- 4- -methyl-
tricyclo[4. 4. 0. 02 S]deca- 3, 8-diene- 7,10-
dione fifi and Isomers fifi, 21 and fig.

Mass Spectrum of l-Methoxymethyl-2-methyl-

cis—3,4-carbonyldioxycyclobutene fifi .

Mass Spectrum of l-Methoxymethyl-Z-
methylcyclobutadieneiron Tricarbonyl fifi

Mass Spectrum of 1-(NN-Dimethyl amine)-
methyl-2-methylcyclobutadieneiron
Tricarbonyl fifi. . . . . .

Mass Spectrum of l-(+)-a-Methoxy-a-
trifluoromethyl-a-phenylacetoxymethyl-2-
methylcyclobutadieneiron Tricarbonyl Zfi

Mass Spectrum of 2,2,3,3-Tetracyano-5-
methoxymethyl-6-methy1bicyclo[2.2.0]-
hex-S-ene Zfi and Isomers fifi, fifi, and fig .

Mass Spectrum of 3-Methoxymethy1- 4-methy1-
8- azatricyclo[4. 3. 0. O2 S]nona- 3- ene- 7, 9-
dione- 8-pheny1 fi4 and Isomers fifi, fifi. and

3&1

Resolution and Decomposition Data

vi

Page

80

81

82

83

84

85

86
87

LIST OF FIGURES

FIGURE Page
1 a) Nmr spectrum of g in deuterochloroform,
b) Spectrum of w1th Eu(DPM)3,
c) Spectrum of from racemic fifi with

Eu(hfbc)3 d) Spectrum of 12 from 46. 3% (+)
gfi with Eu(hfbc)3, peaks marked X are from
U(hbe)3.. . . . . . . . . . . . . 41

2 Infrared spectrum of 1- -methoxymethyl- 2-
methyl- cis- 3, 4- carbonyldioxycyclobutene

Q; (nea—T_. . . . . . . . . . . . . . . . . 57

3 Infrared spectrum of 1- -methoxymethyl- 2-
methylcyclobutadieneiron tricarbonyl fifi
(neat). . . . . . . . . . . . . . . . . 58

4 Infrared spectrum of l-(NN-dimethyl amine)-
methyl-2-methylcyclobutadieneiron
tricarbonyl fifi (neat) . . . . . . . . . . . 59

5 Infrared spectrum of l-(+)-a-methoxy-a-
trifluoromethyl- a- phenylacetoxymethyl- 2-
methylcyclobutadieneiron tricarbonyl .Zfi
(neat). . . . . . . . . . . . . . . . . 60

6 Infrared spectrum of 2,2,3,3-tetracyano-
5- -methoxymethy1- 6- -methylbicyclo[2. 2. 0]-
hex- 5- ene 12 and isomers fifi, .fifi. and .fifi
(neat). . . . . 61

7 Infrared spectrum of 3- -methoxymethyl- 4-
methyl-8-azatricyclo[4. 3.0. 02 S]nona- 3-
ene- 7, 9- dione- 8- -phenyl fi4 and isomers fifi,
fifi and fiZ (neatL . . . 62

8 Infrared spectrum of 3- -methoxymethy1- 4-
methyltricyclo[4. 4. 0. 02 S]deca- 3, 8- diene-
7,10-dione fifi. and isomers fifi, fifi and fifi
(neatL . . . 63

9 Nmr spectrum of l-methoxymethyl-2-methy1-
cis-3,4-carbonyldioxycyclobutene fifi

(Elias) 64

vii

FIGURE
10

11

12

13

14

15

16

17

18

19

LIST OF FIGURES (Continued)

Nmr spectrum of l-methoxymethyl-2-methy1-
cyclobutadieneiron tricarbonyl 88 (CDC13)

Nmr spectrum of 1-chloromethy1-2-methy1-
cyclobutadieneiron tricarbonyl 888 (CC14)

Nmr spectrum of l-bromomethyI-Z-methyl-
cyclobutadieneiron tricarbonyl 888 (CC14)

Nmr spectrum of 1-(N,N-dimethy1 amine)-
methyl-2-methy1cyclobutadieneiron
tricarbonyl 88 (CDC13).

Nmr spectrum of 1-(+)-a-methoxy- -
trifluoromethyl- a- phenylacetoxymethyl- 2-
methylcyclobutadieneiron tricarbony10Z8
from racemic 88 (CDC13) .

Nmr spectrum of 1-(+)-a-methoxy-a-
trifluoromethyl- a- phenylacetoxymethyl- 2-
methylcyclobutadieneiron tricarbonyl 88
from (-) 88 (CDC13) . . . .

Nmr spectrum of l-(+)-a-methoxy-a-
trifluoromethyl- a- phenylacetoxymethyl- 2-
methylcyclobutadieneiron tricarbonyl 18
from (+) 88 (CDC13L.. . .

Nmr spectrum of 3- -methoxymethy1- 4- -methyl-
8- azatricyclo[4. 3. 0. 02 ’ s]nona- 3- ene- 7, 9-
dione- 8- -pheny1 84. and isomers 88, 88 and

QZ (c0013).

Nmr spectrum of 3- -methoxymethy1- 4- -methyl-
8-azatricyclo[4. 3.0. 02 S]nona- 3- ene- 7, 9-
dionL 8- -pheny1 84 and isomers 88, 88 and
88 with Eu(hfbc 3 in CDCI3

Nmr spectrum of 3- -methoxymethy1- 4- -methyl-
tricyclo[4. 4. 0. 02 5]deca- 3, 8- diene- 7, 10-

dione 88 and isomers 88, 81 and 88 (CDCIS).

viii

Page

64

65

65

66

66

67

67

68

69

FIGURE
20

21

22

23

24

25

26

27

28

29

LIST OF FIGURES (Continued)

Nmr spectrum of 3methoxymethy1- 4- -methyl-
tricyclo[4. 4. 0. 02 5]deca 3, 8- diene- 7, 10-
dione and isomers fig, 2i an dgg from
racemic 6% with Eu(hf c)3 1n CDC

Nmr spectrum of 3- -methoxymethy1- 4- -methyl-
tricyclo[4. 4. 0. O2 5]deca- 3, 8- diene- 7, 10-
dione 82 and isomers 3Q, 31 an dgi from
39% (+3 Q; with Eu(hfbc)3 1n CDC

Nmr spectrum of 2,2,3,3-tetracyano-5-
methoxymethyl-6-methy1bicyclo[2.2.0]hex-
S-ene 12 and isomers QQ, g& and fig (CDCl

Nmr spectrum of 2, 2, 3, 3- tetracyano- S-
methoxymethy1-6 methylbicyclo[2. 2. Olhex-
5- ene Z2 (CDC13). . .

Nmr spectrum of 2, 2,3, 3-tetracyano- 5-

methoxymethyl- 6- -methy1bicyclo[2. Z. O]hex— S-

ene 12 with Eu(DMP)3 in CDCl3
Nmr spectrum of Z,Z,3,3-tetracyano-S-
methoxymethyl-6-methy1bicyclo[2.2.0]hex-
S-ene ;g from racemic 62 with Eu(hfbc)3
in CDC 3 . . . . . . . . . . . .

Nmr spectrum of 2,2,3,3-tetracyano-5-
methoxymethyl-6-methy1bicyclo[2.2.0]hex-
S-ene $2 from 46% (+) 62 with Eu(hfbc)3
in CDC 3 .. . . . . . . . . . . . . . .
Nmr spectrum of Z,2,3,3-tetracyano-S-
methoxymethyl- 6- -methy1bicyclo[2.2.0]hex-

S- ene from 39% (-) with Eu(hfbc)
in CDC 3. . .gz. . . . . . . § .

CD spectrum of 52.5% (+) l-methoxymethyl-
2-methy1cyc1obutadieneiron tricarbonyl
62 (pentane).

CD spectrum of 32.2% (-) l-methoxymethyl-
2-methy1cyclobutadieneiron tricarbonyl

6% (pentane).

ix

3)'

Page

69

70

70

71

71

72

72

73

74

FIGURE

30

31

32

33

LIST OF FIGURES (Continued)

CD spectrum of Z,2,3,3-tetracyano-S-
methoxymethyl-6-methy1bicyclo[2.2.0]hex-
S-ene 2 and isomers and 83 from

52.5% +) Q; (cuscuzogggCgii.

CD spectrum of 2,2,3,3-tetracyano-S-
methoxymethyl-6-methy1bicyclo[2.2.0]hex-

S-ene g and isomers 88, I; and 82 from
2 H3 . . . . . . . .

32% (- Q; (CH3CH20CH

CD spectrum of 3-methoxymethy1-4-methy1-
tricyclo[4.4.0.02 S]deca-L8-diene-7,10-

52% (

dione and isomers , and from
32, 321,31. . 3%. . . .

g (CHSCHZOCH

CD spectrum of 3-methoxymethy1-4-methy1-
8-azatricyclo[4.3.0.02 5]nona-3-ene-7,9-

dione-8-pheny1 84 and isomers 8§, 86 and

g; from 50% (+) fig (CHC13).

Page

76

77

78

79

INTRODUCTION

The preparation of cyclobutadiene I has been the

1
m

 

 

 

 

research goal of many chemists for several decades. Although
now recognized to have an extremely short lifetime in the
free state at room temperature, I has been found to be a
suitable ligand for forming stable complexes with appropriate
transition metals. In 1956 Longuet-Higgins first predicted

1 It was not until 1959

that such complexes would be stable.
that a transition metal cyclobutadiene complex was first
reported. Criegee and Schroder prepared 1,2,3,4-tetramethyl-
cyclobutadiene nickel dichloride 3 by treating l,2,3,4-
tetramethyl-3,4-dichlorocyclobutene g with nickel tetra-

carbonyl in benzene.2

 

 

| C1 Ni(CO)4\>

/
.1 @

 

 

 

The potential of cyclobutadiene transition metal
complexes in synthesis, however, was not realized until the

(xxmplex could be dissociated, releasing the four carbon

1

ligand for chemical reaction. Cyclobutadieneiron complexes
have proven to be the most useful in this respect. Pettit

prepared the unsubstituted complex 9 by treating 3,4-

 

 

 

 

 

 

dichlorocyclobutene 4 with diiron eneacarbonyl.3
Cl
FeZ(CO)9
l Cl
Fe(CO)3

4 §

Oxidative decomposition of 9 with ceric ammonium
nitrate (Cer) yields products that would be expected from
a cyclobutadiene intermediate. If no trapping agents are

present, a cyclobutadiene dimer 6 is formed.4

 

 

C6” > NJ JJ

 

Fe(CO)3
,é Q
If there are dienophiles present, such as dimethyl
maleate, 3 gives products identical to those which would

have arisen from a Diels-Alder reaction with l.4 _

 

 

 

 

 

0
CeIV X /
/ H CH3
L OCH3 OCH3
e(CO)3 OCHS 0

The iron complex g has also been shown to react with
cyclopentadiene where the product 8 appears to have arisen

from l reacting as a dienophile.

Ci) CeIV 5 g ‘\

Fe(CO)3
1%

1%

 

 

 

 

Although recently it has been reported that I has been

5’6 there

observed in low temperature photolysis experiments,
has been no conclusive proof of the presence of l as an
intermediate in the oxidative decomposition of cyclobuta-
dieneiron tricarbonyl complexes in the presence of trapping
agents. Pettit and coworkers have reported most of the
information concerning the mechanism of this reaction.

The first observation made about this reaction was the
stereochemistry of the trapped products. Dienophiles such
as dimethyl maleate and dimethyl fumarate were shown to

retain their stereochemistries in the products.

0
H OCH3 IV ’0
C a
8?] * ' e > [a
H OCH3 C=0
I
8a

0 9
-OCH

Big +~ ' 3 e 73> Allull' H
CHSO

=0
F co
{3' e( )3 0 lQ E013

 

Fe(CO)S

§

3

 

 

This fact was used to support the argument that l was
reacting from a singlet electronic state I. A triplet state

reaction should give stereochemical scrambling of the

 

 

 

 

products.4
r— _,
H OCH H ’9
-OCH
0
D + 3 —__>‘ H 3
OCH
H 3
C=O
I O — I -‘
0
CH3
0 __
n r- c-ocH3
C-OCH3 H . H
H C=O é
“ “H \OCH3
C\ = =0 __
0” OCH (.3 0 ‘— (I
3 O 0
£9 8 CH3 CH3

In other experiments Pettit did studies on the oxidative
decomposition of 1,2-diphenyl cyclobutadieneiron tricarbonyl
ll in the presence of dienophiles of varying strengths.

From the examination of the products of these reactions he
found that the moderately reactive dienophiles such as
benzoquinone and N-phenyl maleimide gave only *2 and l3

. . . . 7
although 51x isomers were p0551ble in each case.

 

 

 

 

 

 

 

0
¢\
...
/
¢ Fe(CO)3 0
It
0
¢
+ I N-¢
¢
Fe(CO)3 O
11
'\:’\a

 

Extremely reactive dienophiles such as tetracyanoethylene
and 1,2-dicyanomaleimide gave two isomers lg, lg and l6, lz

respectively, of the three and six possible respectively.7

CN CN
_..__> ... + w. ~
CN N ¢ CN ¢ CN

 

 

¢ Fe(CO)3
11 t3 I8
0
451$] Cm-” Cer >
¢ 1=e(CO)_,:C

II

 

T11e unsymmetrical isomers l3 and ll were in a sevenfold excess

of IA and “3 respectively.

To explain these results Pettit suggested that l was
rectangular in nature. Therefore, 1,2-dipheny1 cyclobutadiene
itself would exist in two isomeric forms lfia and lgb as

shown below.

 

 

 

 

 

 

 

 

kit .l lit

He suggested that there is an equilibrium between lQQ
and lgb and because of the sensitivity of Diels-Alderg
additions to steric effects, it is expected that lgb is
more reactive as a diene than lga. With moderately reactive
dienophiles, the rate of interconversion of lfia and lfib is
fast compared to the Diels-Alder addition and the reaction
with the dienophile proceeds via the more reactive isomer
(i.e. lfib). For the extremely reactive dienophiles the rate
of addition is fast compared to the interconversion rate.
This equilibrium lies in favor of lfia.

One might therefore be tempted to draw the conclusion
from these experiments that cyclobutadiene l is reacting from
a singlet electronic state. But this conclusion is based
on the assumption that l is free in this reaction and its
reactivity is not at all affected by the metal. This
assumption has not yet been established by experimental fact.
Before valid conclusions can be drawn about the electronic
state of l, one must prove that free l is indeed involved in

the mechanism in the trapping step.

Pettit and coworkers realizing this, proceeded to rule
out experimentally what they considered to be the four
alternative pathways which would not involve a free l inter-
mediate. First, they considered the possibility that the
iron complex and dienophile reacted directly. This
possibility was eliminated by mixing 3 and dienophiles such
as dimethyl maleate together without an oxidizing agent
present. They observed no trapped product formation.8

0
OCH

+ | 3 -—————E> No Reaction

OCH

 

 

 

 

Fe(CO)3

é

The second possibility was that the dienophile complexed
to the neutral metal complex by replacing one of the carbon
monoxide ligands followed by an intramolecular addition to
the cyclobutadiene still coordinated to the metal. This
possibility was eliminated by photolyzing dimethyl maleate
or dimethyl fumarate with 3 and isolating products l9 and
2Q which contained one dienophile complexed to the neutral

metal complex.8

CH

+ l 3 hv 3 [Si

 

 

 

 

CH

 

CH

Fe(CO)
Fe CO 2
( )3 0 OCH

é *2 O

OCH

 

 

 

 

 

 

 

 

CH3 CH
Fe(CO)3 o Fe(C0)z

CH
é

458

The substitution products *9 and {Q are stable and thus
undergo no further intramolecular reaction if an oxidizing
agent is not present. These experiments also show that an
oxidizing agent is involved in getting the desired chemical
reaction.

The third possibility, they considered was that a
dienophile could replace a carbon monoxide and then add to

the coordinated cyclobutadiene during the oxidation.

 

CH
3 ———->

| <—— OCH
CH . 3

3 P CO
Fe(CO) 3 e( )2 OCH

O
Q 5&2 0 2

 

 

 

 

To test this possibility, Pettit did a competition
experiment with the isomeric iron substitution products l9
and gQ in the presence of the opposite isomer of the

dienophile as is shown on the following page.

 

 

 

 

OCWl/‘LOCH 13—) 1 : 25
(CO)2 I-l CH3 0
OCH .30 OCH3
OCH H

/ OCH

 

OCH:5

Lfl:::OCH:h-I_$
(c0) Meg

Decomposition of an equal molar concentration of £9 and

 

 

 

dimethyl furmarate gave a mixture of g and kg in a ratio of
1:25 as shown above. Decomposition of an equal molar
concentration of {Q and dimethyl maleate gave a mixture

of g and kg in a ratio of 1:50. Pettit reasoned that if the
third possibility was the mechanism, the adduct derived from
the substituted iron complex would be the major product in
each case. That is, the reactiOn containing lg should give
predominantly 9 and the reaction containing 2Q should give
predominantly lg. He rules out then the third possibility
noting that the major product in each case is that adduct

of fumarate which is the more reactive dienophile.8

10

The fourth possibility considered by Pettit was that
the products could arise from external attack on some
oxidized form of the iron complex. Since the oxidized iron
complex would be a cation or cation radical he reasoned that
if 3 were decomposed in the presence of an equal molar amount
of 1,1-dipheny1 ethylene and dimethyl maleate, the product
would be predominantly that one derived from the best cation
trap, i.e. from 1,1-diphenyl ethylene. When this experiment
was performed and only the dimethyl maleate adduct 9 was
observed, he concluded that this fourth possibility was not
Operating.8

After ruling out these possibilities, Pettit did an
experiment which he used to illustrate that l is free during
the reaction. A solution of the complex 3 in alcohol was
added to a flask at 0° containing ceric ammonium nitrate in
water. The gases evolved from the reaction were collected
in a trap at -193°. This trap was then treated with an

etheral solution of carbomethoxyacetylene. Warming to room

temperature and a vpc of the ether solution showed small

amounts of methyl benzoate 22.9 0
ll
COZCH3 C-OCH3
* Ce” —9 [U 95% <5
Fe(CO)3 k VPC

“123° -193° gg
00

s-CO CH

2 3

11

This experiment however has come under attack because
to its nonreproduceability and it also gives no information
about the possibility of competing reaction mechanisms. The
question of whether I is free during the reaction still
remains unanswered.

In addition to those possibilities considered by Pettit,
there is an attractive alternate mechanistic possibility,
related to Pettit's fourth possibility and still consistent
with the experimental observations, for formation of adducts
without involving free I. This mechanism results from
thinking of the reaction in terms of transition metal and
coordination chemistry (for example, consider Pettit's
fourth possibility in terms of the coordinating ability of
the dienophiles instead of their cation trapping ability and
dienophile strength). A cyclobutadieneiron tricarbonyl
complex, before oxidation by ceric ions, involves an iron
in the zero oxidation state and is coordinately saturated.
The iron cannot therefore add anymore ligands in this
oxidation state without losing one of the already coordinated
ligands. However during the reaction the ceric ions oxidize
the iron by removing electrons from the iron complex. The
iron therefore in the oxidized state becomes coordinately
unsaturated and can accept electrons in the form of ligands
(previously referred to as dienophiles). In the oxidized,
again coordinately saturated, form, the ligand can react
with the cyclobutadiene ligand while still attached to the
iron. The scheme below summarizes the new mechanistic

possibility.

12

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OCH3
" "Z+ OCH3
Z ] C IV
I
e(CO) 3 _ Fe(CO)3(
Irgn (0) (é
coordinately Iran (111 V/
saturated coor inate y
unsaturated
d18 electrons d16 electrons __
.... 2+ 0 2+
H4) 9 OCH
.———— QOCH <f—‘—‘ £e(CO)3 3
(co), . C\=O H. OCH;
CeIV __ OCH __ 0 ..l
gé Iron (II)
\V coordinately
saturated
d18 electrons
H
1!
“OCH3
C=O
‘CCH
a 3

The experiments of Pettit do not rule out this mechanism.
The experiments which ruled out the first two possibilities
considered by Pettit still apply and for the same reasons
as stated by Pettit. The experiment ruling out the third
possibility considered by Pettit is still consistent with
this new postulated mechanism since dimethyl maleate's and
dimethyl fumarate's ligand coordinating ability parallel
their dienophile strength. Careful examination of the
‘product ratios reveals an actual favoring of the coordinated

ligand. This can be explained by a solvent molecule

occasionally entering the coordination sphere instead of

the free ligand.

Q 0
L OCH3 CH 30
e(CO)2 0C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

O
solvent or ’1
— __ 2+
I Products determined
CO p .—_;> by more strongly
( )2 e coordinated ligand
0 I i.e. fumarate
CHSOWOOE:
Q/ __ OCH3 __
85%
T 7 2+
CD 0
Products will favor ligand
(co) Fe OCH3 originally coordinated to
2 OCH ""9
i 3 the neutral complex
solvent 0
molecule

 

£1

14

The actual distribution of 9 and IQ will be a
combination of the effects of the intermediates 26 and 22.
The competition experiment of 3 for dimethyl maleate and
l,l-diphenyl ethylene can be easily rationalized on the
basis of ligand coordinating ability. Dimethyl maleate is
not only a better dienophile but also a much better ligand
than l,l-diphenyl ethylene. Therefore the results of
Pettit's fourth experiment are entirely consistent with the
new mechanism.

One is then left with the question of how to prove that
the reaction mechanism either involves a free I, or an
oxidized coordinated iron is still attached to the cyclo-
butadiene ligand in the trapping step. An examination of the
symmetries of the two possible types of intermediates suggests
an experiment which would answer the question. The two

intermediates under consideration are;

 

 

 

 

 

 

 

I ' or

R:)+-1
Fe(CO)
1 R 3

 

 

 

If appropriate substituents X and Y were placed on the
cyclobutadiene moiety in the l and 2 positions, one notices
that intermediate 28 becomes chiral while intermediate I

remains achiral.

15

 

 

 

 

 

 

 

 

 

 

r-' X ——~n+
X
/| | or Y
Y Fe(CO)
// 3
H 1“}
__J

“’R «7352

An optically active iron complex being trapped as free 29
will go through an achiral transition state and will give
racemic trapped products. An optically active iron complex
going through an intermediate type 3Q in the trapping step
will go through a chiral transition state and will give
optically active trapped products. The scheme below outlines

the two possible pathways.

 

 

 

 

 

 

 

 

 

 

 

 

r -n+ R
x YIV x Y x fit H
(9 “1+ ——> I I __.> y. -
Fe (CO) 3 Femmg .
"‘ £2
ék ég Racemic
optically
active fl::
r- Y _n+
R

 

 

 

 

 

 

 

 

 

 

 

 

. _ 2
W x Y :
RH’
Y Y
(C0)3 e R (C0)3 e\ 41R:e(coj R F (CO)::I

 

R 4,2

17

The trapped adducts of the type éz, QQ, §2 and QQ have
the potential for optical activity since X and Y substitution
and their bent structures give them chirality.

It is interesting to note that in 1972, Green and
coworkers, starting with é and perfluoro olefins isolated
n allyl-o iron compounds Ql, gg similar to the ones proposed

as intermediates shown above.10

F F
+ hV \ F
hexane ’7
F F ‘ F

 

 

 

 

 

Fe(CO)3 (DEC/[Pi
i If (.1.
0 'o a

 

 

 

 

 

F CF3
| hv \ F
Q hexane / F
I F F

OEC//F\ F

C
fl C
0/

801
O

3%

With this background information in mind the oxidative
decomposition of cyclobutadieneiron tricarbonyl complexes

in the presence of symmetrical dienophiles was investigated.

RESULTS AND DISCUSSION

Synthesis of a Chiral Iron Complex

The first goal of this thesis research was to synthesize
a suitable chiral cyclobutadieneiron tricarbonyl complex,
which in general can be depicted as $1 where R1 f R2. The
synthesis made use of the fact that 1,2 disubstituted
complexes such as 31 can be conveniently prepared by a
method developed by Grubbs. Grubbs found that a useful
precursor to 31 can be prepared by photolyzing 1,2
disubstituted acetylenes with Vinylene carbonate gé in
acetone to give the corresponding 1,2 disubstituted, gis-

3,4-carbonyldioxycyclobutene 5% in good yield.11

R

R
I R

c 0\ 1 ,, Na Fe(C0) 1 2
C 0’ )k 1::‘0’ T

A R2 Fe(CO)3

M 44 3,2

 

 

 

 

 

 

The photoadducts 3% can be converted directly to the
corresponding iron complex g1 by treatment with sodium tetra-
carbonyl ferrate (-II).11 The iron dianion can be easily

made by the reduction of iron pentacarbonyl with sodium

18

19

amalgam. Therefore an iron complex with nonidentical R1 and
R2 groups other than hydrogen should be available by using
the appropriately substituted acetylene.

One of the ring substituents on the chiral complex
should be small and inert. The other should contain the
potential to be transformed into a functionality which can
be used as a handle in resolutions. A methyl group seemed
a likely choice for the small inert substituent. The choice
of the functional substituent however was limited by the
photolysis reaction. A satisfactory photolysis product,
l—methoxymethyl-2-methyl-gig-3,4-carbonyldioxycyclobutene
Ql was achieved in a 15% yield with a 40% conversion of 3%

in the following manner.

 

CH

I“ I”
t

T“2 ?”2
C c O\ ,,0\
III + (CH3)ZSO4 + Neon + III + [ C=o 11+) C=o
C c O/ /u\ ago/
I I
C“: CH; 4% 9i

5&2 $29

An acetone solution of l-methoxy -2-butyne QQ and
Vinylene carbonate fig was degassed with nitrogen and
photolyzed through a Pyrex filter using a Hanovia 450 watt
immersion lamp. Removal of the solvent and two careful
distillations yields a bright yellow oil bp 95-105° at

0.5 mm.12

20

The ir spectrum (neat) showed a strong, wide absorption
in the carbonyl region at 1800 cm'1 characteristic of the
carbonate.

The nmr spectrum showed a sharp singlet at 6 3.40 for
the three methoxyl protons. The three allylic methyl protons
show up at 6 1.90 as a broad singlet. The two allylic
methylene protons appear at 6 4.06 as a broad singlet. The
two nonidentical ring protons appear at 6 = 5.3 as an AB
quartet.

The mass spectrum shows no parent peak m/e 170. However
a peak of m/e 126 corresponding to loss of carbon dioxide
from a mass of 170 is observed. This peak and other peaks
at m/e 112 and m/e 95 can be explained from known mass
spectrum fragmentations of cyclobutene carbonates $3.

The reaction described below represents the successful
synthesis of a chiral iron complex, l-methoxymethyl-Z-
methylcyclobutadieneiron tricarbonyl Qg from Q1 in a 12%
yield.12

\

I /(\c=o NaZFe(CO)4 \ o/
‘~d/ THF 1’

 

 

Fe(CO)3

M 32%

A tetrahydrofuran solution of sodium tetracarbonyl
ferrate (-II) was added to a tetrahydrofuran solution
containing the cyclobutene carbonate Q1. Flash distillation

of this reaction mixture separated out the iron dianion and

21

other solid products. Removal of the tetrahydrofuran from

the flash distillate on the rotoevaporator and distillation

of the residue yielded a bright yellow oil bp 55° at 0.5 mm.
The ir spectrum (neat) showed the characteristic iron

1

carbonyl bands with a strong sharp absorption at 2030 cm- and

a strong wide absorption at 1950 cm'l.

The nmr spectrum showed a sharp singlet at 6 1.80 for
the three protons of the ring methyl. A sharp singlet at
6 3.4 appeared for the three protons of the methoxymethyl.
The two ring protons had slightly different chemical shifts,
appearing at 6 4.1 and 6 4.2 as sharp singlets. The two
methylene protons appeared as an AB quartet at 6 3.8, nicely
illustrating the chirality of 62.

The mass spectrum of 6% exhibited the correct parent
peak of m/e 250. Characteristic peaks appeared at m/e 222,
m/e 194, m/e 166 and m/e 110, corresponding to successive
loss of three carbon monoxides and iron respectively.

The iron complex 62, typical of cyclobutadieneiron
complexes is unstable to air and prolonged heating. This
is true of all the other iron complexes synthesized in this

research.

Attempted Resolution of Chiral Iron Complexes

With the experimental details of a synthetic route to
a chiral iron complex worked out, various methods of
resolution were attempted. For 62 to be useful in this
research, the ether function must be able to be converted

into a functionality appropriate for resolutions.

22

It is known in the literature that cyclobutadieneiron
tricarbonyl methyl alcohol 66 can be easily converted to the
chloride 66 by treatment of the alcohol 66 with concentrated

hydrochloric acid.13

 

 

 

[\OH HCl (conc) 5:; 1
5?] /
Fe(CO) 3 Fe(CO) 3

22 Qt

An important feature of the chemistry of the halide 66
thus formed is its high reactivity. In a solvolysis study
of 66 it was found to solvolyze 108 times faster than
benzyl chloride. This high reactivity is attributed to the
greater stability of the a-cyclobutadienyliron tricarbonyl
carbonium ion.14

It was hoped therefore that mild conditions would be
sufficient to cleave the methyl ether of 6%. A carbon
tetrachloride solution of the methyl ether complex 66 was
treated with concentrated hydrochloric acid. The reaction
was followed by vpc. After stirring for 20 minutes the
peak for 6% completely disappeared and no other peak appeared.
Decanting the organic layer gave a carbon tetrachloride
solution of the chloride 666.

An nmr spectrum of this solution is consistent with the
desired chloride. A sharp singlet appeared at 6 1.82 for the
three protons of the ring methyl. The two ring protons show up

at 6 4.05 and 6 4.15 as two sharp singlets. An AB quartet

23

at 6 3.90 appears for the two methylene protons. There
was no sign of an absorption for the methoxymethyl protons
which was previously at 6 3.40.

The l-chloromethyl-2~methylcyclobutadieneiron
tricarbonyl 666 can be easily converted back to the methyl
ether 66 in essentially quantitative yield by treatment
with sodium methoxide in methanol. Again the reaction can

be followed by vpc.

 

 

 

 

 

 

X=(a=C1,
/~\ b=Br)
(Y/ HX E; X
<:NaOMe
e(CO) 3 M80“ Fe (c0) 3

8% 82

It was found that the above reaction could be
performed just as easily with concentrated hydrobromic acid.
An nmr spectrum of the bromide 666 showed a sharp singlet
at 6 1.82 for the three protons of the ring methyl. An AB
quartet at 6 3.80 for the two methylene protons and two
sharp singlets at 6 4.05 and 6 4.12 for the two ring protons.
Now that a chiral iron complex with a potential handle
for resolution was successfully synthesized, methods of
resolution had to be considered. Since an iron complex
which is 100% optically pure is not essential for the trapping
experiment, a kinetic resolution of 66 seemed to be a possibly

simple, direct approach to at least a partial resolution.

24

The reaction between the d and 2 mixture of the cyclo-
butadienyl halide 66 and an optically pure amine would
undergo a displacement reaction whose transition states
between the d-cyclobutadienyl halide 66 with the optically
pure amine and the l-66 with the optically pure amine would
be diastereomeric. Therefore the transition states would
have different energies. If the difference in energies of
the transition states were great enough, the differences in
rate of reaction of the two enantiomers will enrich the
starting d, 2 mixture in either the d or the 2 enantiomer.
This type of experiment was tried using strychnine 66 as

the optically pure amine.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GI) C1 + salt of
Fe(CO)3 8% 98 8Z6
8%
NaOMe \> ‘/
MeOH 17' C?

Fe(CO)3

9%

25

One half equivalent of strychnine 66 was stirred with
666 in benzene for 72 hours at room temperature. The
solution was washed thoroughly with 10% hydrochloric acid
to remove any remaining strychnine. The remaining chloride
complex 666 was treated with sodium methoxide in methanol
to form the methyl ether 66. After washing the organic
layer with water, drying and filtering,a polarimeter was
taken. The rotation was very small, 0.009° at 578 nm.

Several further attempts at kinetic resolutions with
strychnine were made but polarimeter readings seldom exceeded
0.01° at 578 nm. Kinetic resolutions were also attempted
using d-a(1-naphthyl) ethylamine as the resolving agent
however results of these were also unsatisfactory.

Convinced now that the results from the kinetic
resolution approach would not be acceptable, fractional
crystallization of diastereomeric salts was the next
approach used to attempt to resolve the iron complex 66.
The iron complex 66 was converted to the bromide 666 and
then reacted with one equivalent of strychnine 66 in benzene.
It was hoped that the fractionally crystallized
diastereomeric salts thus formed could then be reconverted

to the ether complex 66 with sodium methoxide in methanol.

 

 

 

 

 

 

99

 

 

 

 

 

 

\ .
NaOMe fractionally
We MeUH <crystallize

Fe(CO)3

9%

 

We

This approach however was seen to be impractical when it
was found that the conversion from 616 to 66 went in a 5%
yield.

Next it was decided to further functionalize the a-
cyclobutadienyl halide 666 in order to get a better handle

for resolutions. The two foremost possibilities were:

 

 

 

 

 

 

 

 

 

 

 

OH' OH
> ID
Fe(CO)3
Br 68
Q m
H\N /CH3
Fe(CO)3 \C \ N<
Qék Fe(CO)3

82

27

The synthesis of the amine complex 66 was attempted

first since the alcohol complex 66 would have to be reacted
with phthalic acid before it could be reacted with a
resolving agent l-(NN-dimethyl amine)methy1-Z-methylcyclo-
butadieneiron tricarbonyl 66 was successfully prepared by
stirring the bromide complex 666 and a large excess of
anhydrous dimethyl amine in pentane at 0° for 6 hr.
After warming to room temperature the organic layer was
washed with water, dried and filtered. Removal of the
solvent and distillation of the residue yields a bright
yellow oil bp 56° at 0.5 mm.12

The ir (neat) spectrum exhibited the characteristic

iron carbonyl bands, a strong sharp absorption at 2030 cm-1

and a strong wide absorption at 1950 cm-1.
The nmr spectrum showed a sharp singlet at 6 1.90 for the
three protons of the ring methyl. A sharp singlet at 6 2.33
for the six NN-dimethyl protons. A broad singlet at 6 2.90
appeared for the two methylene protons. Two sharp singlets
at 6 4.1 and 4.12 showed up for the two ring protons.
The mass spectrum of 66 showed the correct parent peak
of m/e 263. Peaks characteristic for iron carbonyls
appeared at m/e 235, m/e 207, m/e 179 and m/e 123
corresponding to successive loss of three carbon monoxides
and iron respectively.

Attempts were then made to resolve the amine complex

62 with a-tartaric acid 16 in methanol.

28

 

 

 

 

 

o
c-on
cuon ' H E
N: ' MeOH > til-'8)" \CHOH
CHOH 1 I
CHOH
Fe(c0)3 c=o Fe(CO)3

82 19 1%

Upon sitting for two days at room temperature, no
crystals fell out of solution. Reduction of the temperature
or the amount of solvent also did not induce crystallization.
Removal of all of the solvent revealed no crystals, but
instead a gel was formed. Another optically active acid
was then sought as a resolving agent.

D-10 camphor sulfonic acid 16 was the next acid reacted

12

with the amine complex 66. Dissolution of 66 and 16 in

hot ethanol and cooling the reaction mixture to room

I
”\80 H szO H-N
was £03 —°—> SE02 "6“

Fe(CO)3 Fe(c0)3

82 1% Zé

 

temperature yielded white crystals Z6 after 48 hrs. Cooling
this mixture at 0° caused further crystallization. After
doubling the volume with diethyl ether, the reaction mixture

was centrifuged and the liquid decanted from the crystals 16.

29

The crystals were then washed several times with a 50/50 v/v
ethanol, diethyl ether solution. The salt 66 was treated
with aqueous sodium hydroxide and the free amine 66 was
extracted into diethyl ether. The ether layer was dried,
filtered and evaporated down to 6 m1. A polarimeter reading
of this solution exhibited a rotation of (+)0.238° at 578 nm.
The decantate of 66 was treated in a similar manner and
revealed a polarimeter reading of (-)0.215° at 578 nm. The
magnitudes of these rotations were judged satisfactory enough
to pursue this approach to optically active iron complexes.
The amine functionality of 66 however is unstable toward
the oxidative decomposition conditions. The dimethyl amine
was thus converted to the quaternary salt 66 by stirring 66

with methyl iodide in ether for 24 hr.

19

 

 

 

 

 

 

 

 

 

 

Io ,
N/ CH31 N- NaOMe; A0
\ :> ' MeOH
Fe(CO)3 Fe(CO)3

Fe(CO)3
Q2 1% Qé
The quaternary salt Z6 was then treated in situ with
sodium methoxide in methanol at room temperature for 16 hr.
Washing the ether layer with two portions of water, drying,
filtering and removal of the solvent gave crude 66 in
essentially a quantitative yield (as determined by Vpc).

Three micro-distillations of this crude 66 afforded pure 66}2

30

The previously mentioned amine complex 66 which exhibited
the (+)0.238° rotation at 578 nm, when subjected to the above
reaction conditions gave crude 66 which showed a rotation of
(+)0.347° at 578 nm. After three micro-distillations, 180 mg
of 66 gave the following polarimeter readings in tetra-
hydrofuran, (+)0.266° at 578 nm, (+)0.322° at 546 nm, and
(+)0.838° at 436 nm.

A question yet to be determined about this resolution
is how effectively does the fractional crystallization
separate the enantiomers. A method for determining the
optical purity of the iron complex was then sought. Treatment
of 66 with a chiral europium shift reagent, tris[3-(hepta-
fluorobutyryl)-d-camphorato]-europium(III) [Eu(hfbc)3] did
not split out any nmr absorptions. The complex seemed to
be chemically unstable in prolonged contact or in an excess
of the shift reagent.

The method found to determine the optical purity of 66
involved the conversion of the ether complex 66 to the
bromide 666 and subsequent reaction of 666 with the potassium

salt of (+)a-methoxy-a-trifluoromethyl-a-phenylacetic acid

 

Z6 in tetrahydrofuran for 5 hr.12
8H3 o CF3
’“\13 l 3 E 6 0M
r - - - e
E + ‘”"f'°'°o "6 3L9 TEE/N) \
' ¢
Fe(c0)3 CF3 Fe(c0)3
We
16 1!;
d and 1 d d + d and d + 2

31

The tetrahydrofuran solution was washed with salt
water, dried, filtered and the solvent removed giving the
crude diastereomeric esters 66. An nmr spectrum was taken of
the crude Z6 and after several u-distillations yielding purer
m-

The nmr spectrum revealed that only two sets of the
protons showed up as diastereotopic protons. The three
protons of the ring methyl appeared as two sharp singlets
centered at 6 1.73 with each absorption integrating to
1.5 protons. One of the ring protons showed up as two
sharp singlets centered at 6 4.08 each integrating to 0.5
proton. The other ring proton appeared at 6 4.18 as a sharp
singlet. The three protons of the methoxymethyl appeared at
6 3.58 as a broad singlet. The five phenyl protons showed
up at 6 7.47 as a broad singlet. An AB quartet appeared at
6 4.73 for the two methylene protons. The fluorine nmr
spectrum showed a broad singlet for the three fluorines of the
the fluoromethyl.

The ir spectrum (neat) shows the characteristic iron

1

carbonyl bands with a strong sharp absorption at 2140 cm- and

a strong wide absorption at 1970 cm'l. Another strong

carbonyl absorption appears at 1750 cm-1.
The mass spectrum of 66 exhibited the correct parent
peak of m/e 452. Characteristic peaks appeared at m/e 424,

m/e 396, m/e 348,and m/e 292, corresponding to successive

loss of three carbon monoxides and iron respectively.

32

A 40 mg sample of 66; rotation = (-)0.037° at 578 nm,
(-)0.047° at 546 nm and (-)0.151° at 436 nm, was converted
into the diastereomeric ester 66 in the above manner. An
optical purity of 50% was calculated for the starting complex
66 by measuring the difference in area of the diastereotopic
ring methyls. The specific rotation of 66 was calculated
to be ll.2° 1 3% at 578 nm. By comparison with this
experiment, all further resolutions produced optical
purities for the positive rotamers from 39 to 79%. The
negative rotamers varied from 23 to 50% in optical purity.

An interesting prOperty of the resolved complex 66
is that upon heating at 120° in xylene for 48 hr. less than
5% racemization of 66 is observed. This should be compared
to a related butadieneiron complex, (+)tricarbonyl(methyl-S-
formylpenta-Z,4-dienoate)iron 66 which racemizes with tl/Z =
46.5 hr. at ll9.4°.

Since electron-withdrawing groups normally stabilize
metal-olefin complexes and racemization requires
decomplexation of at least one of the double bonds of the
diene, the predicted half-life of racemization of a butadiene
complex analogous to the cyclobutadiene complex 66 should be
less than 46.5 hr. at ll9.4°. The much slower racemization
rate of the cyclobutadiene complex 66 must be due to the
requirement that the cyclobutadiene ligand must become
completely detached from the metal in order for racemization

to occur, whereas, the butadiene complex requires the

33

decomplexation of only one bond in the racemization process

as shown below.12

/x
YflxfiY/\ x :2ij—

\

I \ \
Fe(C0)3 Fe(CO)3 Fe(CO)3

22 u
YV" <==2 .../”(x— X

Fe(CO)3
Fe(CO)3

11
With a route to an optically active ether complex 66
of known optical purity available, the decomposition in the

presence of dienophiles could be attempted.

The Decomposition of the Chiral Iron Complex

Optically active 66 was decomposed with ceric ammonium
nitrate in the presence of three dienophiles; either

tetracyanoethylene 66, or N-phenylmaleimide 66, or benzo-

quinone 66. The general procedure for decomposition is
described below.

The ether complex 66 was stirred with an equal molar
zunount of the dienophile in acetone (the tetracyanoethylene
‘66 reaction was done in tetrahydrofuran). The ceric

ammonium nitrate was added as a powder over a 3.5 minute

Ineriod. The reaction mixture was allowed to react until the

34

carbon monoxide bubbles ceased. Diethyl ether was added

and the reaction mixture was washed with portions of salt
water until the aqueous layer remained colorless. The
organic layer was dried, filtered and the solvent removed
leaving the adducts in essentially a quantitative yield.
When optically active ether complex 66 was used, the solvent
was reduced to 6 m1 and a polarimeter reading taken before

the solvent was completely removed.
I

0 CN N

1!. N + [1. CN
CN N
CN /0 CN

 

 

 

 

CN CN
0’ I a.” 12 6g
+ I
CN CN

9% 1% CN

Q6 Qé

The ir spectrum (neat) of the mixture 66, 66, 66 and 66

1

showed a weak sharp absorption at 2240 cm- for the cyano grumps.

The nmr spectrum of the mixture of 66, 66, 66 and 66 showed
that 66 was the major isomer formed comprising about 50% of the
mixture. Three sharp singlets appeared at 6 3.43, 6 3.40 and
6 3.33 for the methoxyl protons. Three broad absorptions at
6 4.20, 6 4.03 and 6 3.80 account for the methylene and ring

lprotons. A vinyl absorption appears at 6 5.5 for isomer 66 and

35

two vinyl absorptions of equal intensity appear at 6 6.36 and
6 6.46 which were assigned to isomers 66 and 66. The other
methyl absorptions show up at 6 2.08, 6 1.73 and 6 1.9.

Isomer 66 could be isolated from 66, 66 and 66 by
tituration of the oily mixture with diethyl ether and washing
the precipitate with cool chloroform. Pure 66 is a white
solid with a melting point of 124-125°. The nmr spectrum of
66 showed no absorptions in the vinyl region. A broad
singlet at 6 2.08 appeared for the three protons of the
allylic methyl. A sharp singlet appeared at 6 3.45 for the
three methoxyl protons. One ring proton showed up at 6 4.0
and the other at 6 4.1, both as broad singlets. The allylic
methylene appeared at 6 4.22 as a broad singlet.

The mass spectrum of 66 and the mixture 66, 66, 66 and
66 showed the correct parent peak of m/e 238.

The mixture of 66, 66, 66 and 66 showed a In!

absorption from 345 to 200 nm with a slight shoulder at

 

 

 

270 nm.
0 4 66 0
Wm/ + D - Cer gm
¢ 0
Fe(CO):5 O ‘/n\

9&6 8L?»

 

36

The ir spectrum (neat) of the mixture of 66, 66, 66 and 66

1

exhibited strong wide absorptions at 1690 cm- for the

carbonyl bands, and a strong wide absorption at 2900 cm-1
for the aromatic region.

The nmr spectrum of the mixture of adducts 66, 66, 66 and
66 showed that by far 66 was the major isomer comprising about
75% of the mixture. The isomer 66 showed a broad singlet
at 6 1.83 for the allylic methyl, a sharp singlet at 6 3.33
for the methoxyl, a multiplet at 6 3.57 for the four ring
protons, a broad singlet for the allylic methylene at 6 3.93
and a complex multiplet at 6 7.5 for the aromatic protons.
Separate absorptions appearing for the other isomers were;
vinyl absorptions of equal intensity at 6 6.03 and 6 6.17
assigned to isomers 66 and 66, a vinyl absorption at 6 5.53
assigned to isomer 66, one other methoxyl absorption as a
sharp singlet at 6 3.4, and other methyl absorptions at
6 1.73 and 6 1.27.

The mass spectrum of the mixture 66, 66, 66 and 66 showed
a correct parent peak of m/e 283.

The mixture of the adducts 66, 66, 66 and 66 absorbed

in the uv from 340 to 200 nm in chloroform.

 

 

 

 

 

The ir spectrum (neat) of the mixture of adducts 66, 66, 66
and 66 exhibited a strong carbonyl absorption at 1675 cm-1‘

The nmr spectrum of the mixture of adducts showed 66 as
the major isomer formed comprising about 45% of the mixture.
Absorptions assigned to the methoxyl protons appeared at
6 3.3, 6 3.40 and 6 3.43 as three sharp singlets. The other
methyl absorptions appeared at 6 1.5, 6 1.57, 6 1.63 and
6 1.93. A complex multiplet appeared in the region of
6 3.5-4.1 for the methylene and ring protons. The two vinyl
absorptions of equal intensity appearing at 6 5.62 and 6 5.90
were assigned to isomers 66 and 66. The carbonyl vinyl
absorptions appeared at 6 6.9 as a complex multiplet.

The mass spectrum of the mixture showed the correct
parent peak of m/e 218.

The mixture of adducts absorbed in the 1nr from
400 to 200 nm with a slight shoulder at 285 nm.

When decompositions of (+) or (-) optically active

ether complex 66 were performed in the presence of either

68 or 83 or 88, a polarimeter reading of the reaction
’b ’b’b 'b’b

38

mixture in diethyl ether revealed racemic adducts t 0.003.
Starting polarimeter readings of optically active 66 were
on the order of 0.10° at 578 nm.

As a more sensitive probe of optical activity, circular
dichroism spectra were taken of starting optically active
ether complex 66 and the decomposition adducts. The
circular dichroism spectrum of the (+) rotamer of 66 in
pentane showed two maxima. One maximum at (+) 310 nm and
the other maximum at (-) 250 nm. The circular dichroism
of the (-) rotamer of 66 in pentane showed a maximum at
(-) 310 nm and another at (+) 250 nm.

The tetracyanoethylene adducts, benzoquinone adducts
and N-phenyl maleimide adducts which arose from both (+) or
(~) 66 exhibited a circular dichroism curve identical to
that of the baseline 1 0.0002° from 450 to 225 nm.

The polarimeter and circular dichroism studies indicate
racemic adducts. However, because each mixture of the
adducts contains four isomers, the possibility exists that
some isomers may have different signs of rotation than
others, the resultant magnitude of the rotation of the
adducts may be very small. Also the possibility exists that
the specific rotation of the adducts may be much smaller
than that of the starting complex 66.

Since the diastereomeric ester complex 66 had been
successful in showing the relative amounts of (+) and (-)

66, the decomposition of 66 in the presence of a dienophile

39

might show diastereomeric splitting in the adducts. When 66
was decomposed in the presence of tetracyanoethylene 66, an
nmr of the adducts revealed no diastereotopic splitting of
any sets of protons.

Since the adducts from the three different dienophiles
all have some sort of nucleophilic functionality, it was
decided to try chiral europium shift reagent experiments
on the various adducts. The chiral europium shift reagent
used was tris[3-(heptafluorobutyryl)-d-camphorato]europium(1II)
[Eu(hfbc)3].

The first adducts tried were the racemic N-phenyl
maleimide adducts 66, 66, 66 and 66, since these adducts
could be purified on a Florisil column and one major adduct
was formed. Addition of Eu(hfbc)3 to a CDCls solution of
the maleimide adducts affected the nmr spectrum mostly by
line broading. However, the phenyl protons split out into
two multiplets which integrated to 2:3.

Eu(hfbc)3 was then tried on racemic benzoquinone
adducts 66, 66, 66 and 66 in chloroform. The europium
shifted spectrum yielded two prominant doublets for methoxyl
protons. By integration studies one doublet was assigned to
the two isomers 66 and 66 which were present in equal amounts.
However the other doublet must be due to splitting out of the
enantiomeric methoxyls of isomer 66. The europium shifted
nmr spectrum of 39% optically pure (+) 66 gave a spectrum
with two methoxyl doublets identical to those of the racemic

complex. The magnitude of nonequivalence of its enantiomeric

40

methoxyls was very small A 0.03 Inmh

Since the tetracyanoethylene adduct 66 could be
separated out as a single pure isomer from 66, 66 and 66
europium shift reagent experiments were tried on 66 in order
to get a simpler clean spectrum. A chloroform solution of
66 from racemic 66 when treated with the achiral shift
reagent tris(2,2,6,6-tetramethylheptanedionate)europium
[Eu(DMP)3] gave a simple, clean and well resolved shifted
spectrum. The three methoxyl protons absorbed at 6 4.75
as a sharp singlet. The allylic methylene appeared as a
multiplet at 6 5.6 integrating as two protons. The ring
protons shifted out a little with one proton appearing at
6 4.1 and the other proton at 6 4.3 as broad singlets. The
three protons of the allylic methyl appear at 6 2.3 as a
broad singlet.

A sample of 66 in chloroform which came from racemic
ether complex 66 was then treated with the chiral shift
reagent Eu(hfbc)3. The shifted spectrum showed two sharp
singlets at 6 4.43 and 6 4.53 which correspond to the
enantiomeric methoxyls. The other proton absorptions appeared
similarly as they did in the achiral europium shifted spectrum.
A sample of 66 from 46.3% (+) optically active 66 and a
sample of 66 from 38.6% (-) optically active 66 were treated
with Eu(hfbc)3, both showed two sharp singlets for the
methoxyl which integrated identical (t 2%) to the above

sample from racemic complex (See Figure l).

Figure 1.

X
., - .' ' Jx a ' (we) I
“'56."..1‘4N VA" «‘1 {a ' x’l’xW” Mfrlfirm'fl '1“
FL

11.131-22'1'7’7'” -1--J-i- 1-1-11 1
.0 I. to 0

41

 

 

.wmfikwwmwmfiAC;jkaWwww#Mdfi;AfiwT

 

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WA? wrNMJAVA WWJ W960"

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a) Nmr spectrum of 66 in deuterochloroform,
b) Spectrum of 66 with Eu(DPM) , c) Spectrum
of 6 from racemic 66 with Eu(fifbc)3,
d) pectrum of 66 from 46.3% (+) 66 with
Eu(hfbc)3, peaks marked X are from Eu(hfbc)3.

42

To insure that the starting ether complex 66 was not
being racemized by the oxidative decomposition conditions,
the following experiment was performed. An ether complex
66 of known Optical purity was decomposed in the presence
of 1 equivalent of tetracyanoethylene 66 by using 1/2
equivalent of ceric ammonium nitrate. A polarimeter reading of
an ether solution of the reaction mixture showed 1/2 of the
starting rotation. Recovery of 66 from the reaction mixture
by distillation yielded ether complex 66 of the same optical

purity as the starting 66.

Conclusion

 

The results from the polarimeter measurements, circular
dichroism curves and europium shift experiments show that
totally racemic adducts are produced from the oxidative
decomposition of optically active 66 in the presence of
symmetrical dienophiles. In order for this to occur, the
transition state must involve an achiral intermediate. The
experimental observations from this work prove that cyclo-
butadiene 6 is free during this reaction . No intermediate
involving cyclobutadiene 6 coordinated to the iron competes
significantly under these conditions.

Further research might be done to see that if under
favorable conditions, 6 reacting while still complexed to
the iron can compete significantly with the reaction of free

6 during decomposition.

EXPERIMENTAL

General Procedures

 

All melting points, determined on a Thomas Hoover
melting point apparatus, are uncorrected.

Ultraviolet spectra were recorded on a Unicam Model
SP-800B; samples were contained in 1 cm quartz cells.
Infrared spectra were obtained using a Perkin Elmer Model
457 spectrophotometer. A Varian T-60 spectrometer was
used to record nmr spectra. Unless otherwise indicated all
spectra are recorded as 6 values in ppm downfield from an
internal standard of tetramethylsilane. Mass spectra were
obtained by Mrs. L. Guile on a Hitachi Perkin Elmer RMU—6
mass spectrometer.

Polarimeter measurements were obtained using a Perkin
Elmer 141 Polarimeter spectrophotometer; samples were
contained in 1 dm (6 cc) quartz cells. Circular dichroism
spectra were obtained with the aid of Dr. John C. Speck Jr.
using a Jasco CD/ORD modified by Sproul; samples were
contained in 1 cm quartz cells.

All gas chromatographs were obtained using a Varian
Aerograph Model 90-P gas chromatograph with a 6' 5% 85-30

VpC column at 130°.

43

44

l-Methoxy-Z-butyne 66.

 

To a cooled solution of 105 g (1.25 m) of 2-butyne-l-ol
66 in 200 ml of water was added 90 g (2.25 m) of sodium
hydroxide and 284 g (2.25 m) of dimethyl sulfate over a 3 hr
period. The reaction mixture was refluxed for 6 hr and
then allowed to stir overnight. Addition of 150 ml of water
dissolved the precipitated salt. The organic layer was
separated from the aqueous layer. The aqueous layer was
extracted with 100, 50 and 50 ml portions of diether ether.
The combined ether and organic layers were dried over
potassium carbonate, filtered and distilled yielding 100 g

(79%) of 66 as a clear liquid: bp 99-103°.

Vinylene Carbonate 66.

 

Chlorine gas was added at a rapid rate to a stirred
solution of 500 g (5.7 m) of ethylene carbonate in 600 ml
of carbon tetrachloride. The reaction mixture was
irradiated with a Hanovia ultraviolet quartz lamp until
complete disappearance of the ethylene carbonate (as
determined by nmr). Distillation yielded 460 g (65%) of
the clear liquid, chloroethylene carbonate: bp 70-76° at
0.5 mm (lit. 106-107° at 10 mm).15

To a stirring refluxing solution of 312 g (2.53 m) of
chloroethylene carbonate in 450 ml of anhydrous diethyl ether
under a nitrogen atmosphere was added 312 g (3.08 m) of
triethylamine (dried by distillation from barium oxide) over

a 6 hr period. After an additional 40 hr of refluxing

4S

(adding ether if needed) the reaction mixture was allowed

to cool to room temperature and then filtered. The brown
precipitate was washed four times with a benzene-ether
solution. Distillation yielded 130 g (60%) of 66 as a clear

liquid: bp 30-36° at 0.5 mm (lit 69-72° at 30 mm).15

1-Methoxymethyl-Z-methyl-cis-3,4-carbonyldioxycyclobutene 66.

 

A degassed solution of 46 g (0.547 m) of l-methoxy-
Z-butyne 66 and 33 g (0.39 m) of vinylene carbonate in 450 ml
of acetone was photolyzed for 14 hr using a Hanovia 450 watt
immersion lamp. Distillation yielded 20 g (60%) of recovered
vinylene carbonate 66: bp 30—38° and 7 g (27%) of 66 as an
orange oil: bp 105-145° at 0.5-1.7 mm. Redistillation of
the orange oil yeilded 5.0 g (19%) of 66 as a yellow oil:
bp 106-ll6° at 0.5 mm; ir (neat) 1800 (strong, wide, C=O)

and 1100 cm-1

(C-O-C); nmr (CDClS) 6 5.30 (q, 2, ring), 6
4.06 (br s, 2, CEZO), 6 3.40 (s, 3, methoxyl), 6 1.90 (br s,
3, methyl); mass spectrum (15 eV) no parent peak, m/e 126

(P-COZ).

l-Methoxymethyl-2-methy1cyclobutadieneiron Tricarbonyl 66.

 

A solution of 2.62 g (0.114 m) of sodium metal in 14 ml
of mercury was treated with 150 m1 of dry degassed tetra-
hydrofuran under a nitrogen atmosphere. To this, 6.5 ml
UL0482n0 of iron pentacarbonyl was added in 2 m1 portions
over a 20 minute period. After the evolution of gases ceased
the sodium amalgam was separated out. Another ml of mercury

was added, stirred and separated out.

46

A solution of 5.0 g (2.94 x 10.2 m) of l-methoxymethyl-
Z-methyl-cis-3,4-carbonyldioxycyclobutene 66 in 100 ml of
dry degassed tetrahydrofuran under a nitrogen atmosphere was
treated with the above sodium tetracarbonyl ferrate (~II)
suspension over a 10 minute period. The reaction mixture
was flash distilled under a 0.5 mm vacuum. Distillation of
the flash distillate yielded 1.0 g (13%) of 66 as a yellow
oil: bp 55° at 0.5 mm; ir (neat) 2030 (strong, sharp, CEO),

1

1950 (strong, wide, CEO) and 1090 cm- (C-O-C); nmr (CDCl

3)

6 3.80 (q, 2, CHZO), 6 4.10 (s, 1, ring), 6 4.20 (s, 1, ring),
6 3.40 (s, 3, methoxyl) and 6 1.80 (s, 3, methyl); mass
spectrum (70 eV) m/e 250 (parent), 222 (P-CO), 194 [P-CO)2],

166 [P-(CO)3] and 110[P-Fe(CO)3]; uv (pentane) 380-200 nm.

l-Chloromethyl-2-methylcyclobutadieneiron Tricarbonyl 666.

 

To a solution of 1.0 g (4.0 x 10-3 m) of l-methoxymethyl-
2-methylcyclobutadieneiron tricarbonyl 66 in 10 m1 of carbon
tetrachloride under a nitrogen atmosphere was added 3 ml of
concentrated hydrochloric acid. The reaction mixture was
stirred for 20 minutes and the organic layer removed, which
gave a carbon tetrachloride solution of 666. This solution
was used directly in subsequent reactions: Nmr (CC14) 6 4.15
(s, 1, ring), 6 4.05 (s, 1, ring), 6 3.90 (q, 2, CflzCl),

6 1.82 (s, 3, methyl).

47

l-Bromomethyl-2-methylcyclobutadieneiron Tricarbonyl 666.

 

To a solution of 1.0 g (4.0 x 10-3 m) of l-methoxymethyl-
2-methylcyclobutadieneiron tricarbonyl 66 in 10 ml of carbon
tetrachloride under a nitrogen atmosphere was added 3 m1 of
concentrated hydrobromic acid. The reaction mixture was
stirred for 20 minutes, the organic layer was removed which
gave a carbon tetrachloride solution of 666. This solution
was used directly in subsequent reactions. Nmr (CC14)

6 4.12 (s, 1, ring), 6 4.05 (s, 1, ring), 6 3.80 (q, 2,
CflzBr), 6 1.82 (s, 3, methyl).

l-Methoxymethyl-2-methylcyclobutadieneiron Tricarbonyl 66

from 666 or 666.

To a solution of 666 or 666 as prepared above along

 

 

with decalin as an internal standard in 10 ml of methanol

was added 0.27 g (5.0 x 10-3

m) of sodium methoxide and
allowed to stir for 1 hr. Enough water was added to
separate the layers. Analysis of the organic layer by

Vpc showed that 66 was reformed in essentially quantitative

yield.

1:LNN-Dimethy1amine)methy1-2-methylcyclobutadieneiron

 

Tricarbonyl 66.

 

To a cooled solution of l-bromomethyl-2-methylcyclo-
butadieneiron tricarbonyl 666 in 30 ml of pentane under a
nitrogen atmosphere was added 10 m1 of dimethylamine in one

portion. The reaction mixture was warmed to room temperature

48

and then washed three times with 30 ml portions of water.
The organic layer was dried with sodium sulfate, filtered
and the solvent removed leaving an orange oil 66. ir (neat)

2030 (strong, sharp, CEO) and 1950 cm'1

(strong, wide, (CEO);
nmr (CDC13) 6 4.12 (s, 1, ring), 6 4.10 (s, 1, ring), 6 2.90
(br s, 12, CfizN), 6 2.33 (s, 6 N-(Cfl3)2), and 6 1.90 (s, 3,
methyl); mass spectrum (70 eV) m/e 263 (parent peak), 235

(P-CO), 207 [P-(c0)2], 179 [P-(CO)3], and 123 [P-Fe(CO)3].

l-Methoxymethyl-2-methy1cyclobutadieneiron Tricarbonyl 66

 

from 66.

To a solution of 0.1 g (3.8 x 10‘4 m) of l-(NN-dimethyl-
amine)methyl-2-methy1cyclobutadieneiron tricarbonyl 66 in
30 m1 of diethyl ether was added 0.284 g (2.0 x 10-3 m) of
methyl iodide. The reaction mixture was allowed to stir at
room temperature for 20 hr. This solution was treated with

20 ml of methanol and 0.54 g (1.0 x 10.2

m) of sodium
methoxide. The reaction mixture after stirring for 20 hr
was treated with water to separate the layers. The water
layer removed and the organic layer washed two more times
with 10 m1 portions of water; dried with magnesium sulfate,
and the solvent removed (vpc analysis shows essentially

quantitative yield of 66 using decalin as an internal

standard). Three microdistillations yielded pure 66.

49

Potassium (+)~a-Methoxy-a-trifluoromethyl-a-phenylacetate.
3

 

To a solution of 0.234 g (1.0 x 10- m) of (+)-a-methoxymr

trifluoromethyl-a-phenylacetic acid in 10 m1 of ethanol was

added 0.0464 g (8.3 x 10'4

m) of potassium hydroxide. After
stirring for 1/2 hr, diethyl ether and water was added
giving two layers. The water layer separated out and then
the water removed leaving .18 g of the acid salt as a white

precipitate.

l-(+)-a-Methoxy-a-trifluoromethyl-a;phenylacetoxymethyl-2-

methylcyclobutadieneiron Tricarbonyl 66.

 

To a solution of 35 mg (1.17 x 10.4 m) of l—bromomethyl-
2-methylcyclobutadieneiron tricarbonyl 666 prepared as
previously described in 30 ml of tetrahydrofuran under a
nitrogen atmosphere was added 40 mg (1.53 x 10-4 m) of
potassium (+)-a-methoxy-a-trifluoromethyl-a-phenylacetate.
After stirring for 4 hr, 20 m1 of diethyl ether and water
was added to give two layers. The water layer was removed
and the organic layer washed several times with a 5%
solution of sodium bicarbonate. The organic layer was dried
with magnesium sulfate, filtered and the solvent removed
leaving a brown oil 66. Microdistillation yields 23 mg (43%)
of 66; bp 100° at(L5 mm; ir(neat) 2140 (strong, sharp, CEO),

1

1970 (strong, wide, CEO), and 1750 cm' (strong, CEO); nmr

(CDC13) 6 7.47 (m, 5, aromatic), 6 4.73 (q, 2, CflZ-O),
6 4.18 (s, 1, ring), 6 4.08 (d, 1, ring, J=4 Hz), 6 = 3.58

m, 3, methoxyl) and 6 = 1.73 (d, 3, methyl, J=6 Hz); mass

SO

spectrum m/e 452 (parent), 424 (P-CO), 396 [P-(CO)2], 368

[P-(CO)3], and 312 [P-Fe(CO)3].

2,2,3,3-Tetracyano~5-methoxymethyl-6-methylbicyclo[2.2.0]-

 

hex-S-ene 72 and Isomers fig, gl and g2.

 

To a solution of 50 mg (2.0 x 10.4 m) of l-methoxymethyl-
2-methylcyclobutadieneiron tricarbonyl 62 and 22 mg of tetra-
cyanoethylene lg in 7 ml of dry degassed tetrahydrofuran

4 m)

under a nitrogen atomsphere was added 390 mg (7.1 x 10-
of ceric ammonium nitrate as a powder over a 4 minute period.
The reaction mixture was allowed to stir vigorously for 15
more minutes. Diethyl ether was added and the organic layer
was washed several times with 7 m1 portions of a saturated
salt water solution until the aqueous layer became colorless.
The organic layer was dried with magnesium sulfate, filtered
and the solvent removed leaving 43 mg (100%) of 72, 60, g1
and Q2 as an orange oil. Isomer 12 can be titurated out as

a solid by addition of diethyl ether to the oil; mp 124-125°

ir (neat) 2240 (weak, sharp, CN) and 1090 cm-1

(C-O-C); nmr

6 6.46 (br 5, vinyl), 6 6.36 (br s, vinyl),6 5.50 (br 5, vinyl),
6 4.20 (m, CEZO), 6 4.03 (m, C320), 6 3.80 (m, C320), 6 3.43,

6 3.40, 6 3.33 (s, methoxyls) and 6 2.08, 6 1.9, 6 1.7 (s,
methyls); mass spectrum m/e 238 (parent peak); uv (diethyl

ether) 345-200 nm, sh 270 nm.

51

3-Methoxymethyl-4-methyl-8-azatricyclol4.3.0.02,5]nona-3-ene-

 

7,9-dione-8-phenyl 66 and Isomers 66, 66 and 66.
T

 

To a solution of 50 mg (2.0 x 10' m) of l-methoxymethyl-

2-methylcyclobutadieneiron tricarbonyl 66 and 32 mg (1.85 x

-4

10 m) of N-phenyl maleimide 66 in 7 ml of degassed acetone

4m)

under a nitrogen atmosphere was added 390 mg (7.1 x 10-
of ceric ammonium nitrate as a powder over a 3 minute period.
The reaction mixture was allowed to stir vigorously for 5
more minutes. Diethyl ether was added and the organic layer
was washed several times with 7 ml portions of a saturated
salt water solution until the aqueous layer became colorless.
The organic layer was dried with magnesium sulfate, filtered
and the solvent removed leaving 50 mg (100%) of 66, 66, 66
and 66 as a tan oil. ir (neat) 1690 (strong, wide, CEO),

2900 cm'1 1

(strong, broad, aromatic), and 1100 cm- (C-O-C),
nmr (CDC13) 6 7.5 (m, aromatic), 6 6.17, 6 6.03, 6 5.53 (br 5,
vinyl), 6 3.93 (br s, CflzO), 6 3.57 (m, ring), 6 3.33, 3.40
(s, methoxyls) and 6 1.83, 6 1.73, 6 1.27 (s, methyls);

mass spectrum m/e 283 (parent); UV (CHCls) 340‘200 nm.

 

3-Methoxymethyl-4-methyltricyclo[4.4.0.02'51deca-318-diene-
7,10-dione 66 and Isomers 66, 66 and 66. '

 

To a solution of 50 mg (2.0 x 10.4 m) of l-methoxymethyl-

2-methylcyclobutadieneiron tricarbonyl 66 and 20 mg (1.85 x

-4

10 m) of benzoquinone 66 in 7 ml of degassed acetone under

4

a nitrogen atmosphere was added 390 mg (7.1 x 10' m) of ceric

ammonium nitrate as a powder over a 3 minute period. The

52

reaction mixture was allowed to stir for five more minutes.
Diethyl ether added and the organic layer washed several
times with 7 ml portions of a saturated salt solution until
the aqueous layer became colorless. The organic layer was
dried with magnesium sulfate, filtered and the solvent
removed yielding 40 mg (100%) of 66, 66, 66 and 66 as a
yellow oil. ir (neat) 1675 (strong, wide, C=O) and 1100 cm-1
(C-O-C); nmr (CDC13) 6 6.9 (m, carbonyl vinyl), 6 5.90,

6 5.62 (br 5, vinyl), 6 4.1-3.5 (m, CflZO and ring), 6 3.43,
6 3.40, 6 3.3 (s, methoxyls) and 6 1.93, 6 1.63, 6 1.57,

6 1.5 (s, methyls); mass spectrum m/e 218 (parent); uv

diethyl ether) 400 to 200 nm, sh 285 nm.

Resolution of 1-(NN-Dimethylamine)methyl-Z-methylcyclobuta-

dieneiron Tricarbonyl 66.

 

A heated solution of 1.05 g (4.0 x 10'3 m) of l-(NN-
dimethylamine)methyl-2-methylcyclobutadieneiron tricarbonyl

69 and 0.928 g (4.0 x 10‘3
'b'b

m) of d-lO-camphor sulfonic acid
66 in 3.5 ml of dry degassed ethanol under a nitrogen
atmosphere was allowed to cool to room temperature for 48 hr.
The reaction mixture was then cooled at 0°C for 24 hr.
Diethyl ether is then added to double the total volume and
the reaction mixture was centrifuged. The yellow liquid

was decanted and the white crystals washed 5 times with a

50/50, v/v ethanol, diethyl ether solution by centrifugation

and decantation.

53

The crystals dissolved in hot methanol were added to an
excess of aqueous sodium hydroxide. The free amine 66 was
extracted into diethyl ether. The ether layer was dried
with sodium sulfate, filtered and the solvent removed.

A polarimeter revealed that the crystals yielded the positive
rotamer and the decantates yielded the negative rotamer. ~
The amine 66 thus formed is used directly in subsequent
reactions. See Table 8 for details of representative

resolutions.

Nmr Experiments with the Trapped Adducts and Eu(hfbc)3.

 

Decompositions of 66 were done as previously described on
pages 49, 50,and 51. As much of the sample as possible was
dissolved in 0.15 ml of deuterated chloroform (note that
with pure isomer Z6, vigorous heating was required to get
dissolution). The solution was transferred to a thick
walled nmr tube and a nmr spectrum was taken. Solid
Eu(hfbc)3 was added in 5 mg portions directly into the nmr
tube. The nmr tube was tipped up and down until the solid
dissolved and the solution was thoroughly mixed. After the
solution was allowed to come to equilibrium at the nmr
spectrometer temperature for 10-15 minutes an nmr was taken.
Further 5 mg portions of Eu(hfbc)3 were added as needed to

obtain a satisfactory shifted spectrum.

54

Decomposition of Optically Active l-Methoxymethyl-2-methyl-

 

cyclobutadieneiron Tricarbonyl 66 with 66, 66 and 66.

 

Decompositions with optically active iron complex 66
with the dienophiles Z6, 66 and 66 were done almost
identically to those with racemic 66. However instead of
completely removing the solvent after filtering, the solvent
was evaporated down to 6 ml and polarimeter measurements
were taken. See Table 8 for details of representative

decompositions.

BIBLIOGRAPHY

10.

11.
12.

BIBLIOGRAPHY

H. C. Longuet-Higgins and L. E. Orgel, J. Chem. Soc.,

 

1969 (1956).
R. Criegee and G. Schroder, Angew. Chem., 66, 70 (1959).

G. F. Emerson, L. Watts and R. Pettit, J. Amer. Chem.

 

§gg., 66, 131 (1965).

L. Watts, J. D. Fitzpatrick and R. Pettit, 1619., 66,
623 (1966).

O. L. Chapman, D. DeLaCruz, R. Roth and J. Pacansky,
i2i§., 66, 1337 (1973).

C. Y. Lin and A. Kranz, J. Chem. Soc., Chem. Commun.,

 

 

1111 (1972).

P. Reeves, T. Devon and R. Pettit, J. Amer. Chem. Soc.,

 

66, 5890 (1969).
P. Reeves, J. Henery and R. Pettit, 1619., 66, 5858 (1969).
L. Watts, J. D. Fitzpatrick and R. Pettit, 121d., 66,
3253 (1965).

A. Bond and M. Green, J. Chem. Soc., Chem. Commun., 12

 

 

(1971).
R. Grubbs, J. Amer. Chem. Soc., 66, 6693 (1970).

 

R. Grubbs and R. A. Grey, J. Chem. Soc., Chem. Commun.,

 

 

76 (1973).

55

56

13. L. Watts, J. D. Fitzpatrick and R. Pettit, J. Amer.

Chem. Soc., 66, 3254 (1965).

 

14. R. E. Davis, H. D. Simpson, N. Grice and R. Pettit,
ibid., 66, 6688 (1971).
15. M. S. Newman and R. W. Addor, ibid., 66, 3789 (1955).

APPENDIX

57

 

Infrared spectrum of l-methoxymethyl-Z-methyl-cis-

3,4-carbonyldioxycyclobutene 66 (neat).

Figure 2.

 

 

Figure 3. Infrared spectrum of l-methoxymethyl-Z—methyl-
cyclobutadieneiron tricarbonyl 66 (neat).

59

 

MIC130NS

4.0

6.0
J 7L
r

23.1”. .

1 I

L444
yr:

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l

II—Ir‘

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Infrared spectrum of 1-(NN-dimethyl amine)methyl-
2-methylcyclobutadieneiron tricarbonyl 66 (neat).

Figure 4.

60

 

 

 

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Infrared spectrum of l-(+)-a-methoxy-a-trifluoro-

methyl

Figure 5.

a-phenylacetoxymethyl-2-methylcyclobutadiene-

iron tricarbonyl Z6 (neat).

~m

.i,- 5'
2:21 a?"
Li :-

 

Figure 6. Infrared spectrum of 2,2,3,3-tetracyano-S-
methoxymethyl-6-methylbicyclo[2.2.0]hex-S-ene
Z6 and isomers 66, 66 and 66 (neat).

 

m

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o l . I» LII-v
4 . I Til-.- ._.- It...” ”tumult-.1.
. u ..- ..u». . -. .....
5 1 le-Iuis -n....|fl....-.-.nun. Hh.......-x-..t
3 LI IIIII Il-III .l1.|.v .
. . r ...; 1.1.. ..
m . ... .r,

   

I‘ll-Ill

    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

16
.1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

nona-3-ene-7,9-dione-8-

2,5]

Infrared spectrum of 3-methoxymethyl-4—methyl-8-
phenyl 66 and isomers 66, 66 and 66 (neat).

azatricyclo[4.3.0.0

Figure 7.

63

 

 

 

 

Figure 8. Infrared spectrum of 3-methoxymethy1- 4-—methyl-
tricyclo[4. 4. 0. 02 s]deca- 3, 8- diene- 7, 10- dione
66 and isomers 6;, 66 and 66 (neat).

fit V r 1 Y T 71 V V V V I V V T Vii rT‘T‘l Y—f' i I 1
77777

T+v fi fi v—ffvaWWWw W rw r'if' v 'v v 'v v v vi
F L L i l Hm

 

fVVvavav'VV

 

 

 

 

 

 

 

 

 

l A AA A A 1 4A A A A A L4 A A A L A A A L A A L 4 A A
g4 _A I A A A A L A A A A L A A A A l J A A J l A A A L A A A A l A A A A r A A A AL
no 15 0! or "a I“ on. J. 70 L0 0
......

Figure 9. Nmr spectrum of l-methoxymethyl-Z-methyl-cis-
3,4-carbonyldioxycyclobutene 66 (CDC13).

 

V V V I
I V T I V V V V I V V U V I T V ffi I V Y fi' V I V V V 1 l U 1 r V I V V 1' V I '

 

 

 

 

 

 

 

500 400 :00 m on 0
...-I.
Fe(CO)
3
/
l
v‘.‘*‘_____“__‘_.._“—— ~— vflvwww AA] W.-
l . i 1 I 1 J 1 J
A..L11-.1-...1.,..1-.--‘I.1..11..1‘r i.-Jii-.I,
u 1.. u ”mun“ M '0 10 O

 

 

 

Figure 10. Nmr spectrum of 1-methoxymethyl-Z-methylcyclo-
butadieneiron tricarbonyl 66 (CDC13).

65

 

T V V V I V V V V l U V V

 

 

 

 

 

 

 

 

 

 

 

'V' flv' 'fV' Vvvr'Y V'V':!" 'VfV'T' I'v'v'r'v' I V V V V I
.L .5 J: :$ " "&' '9? P tn
”0
Cl
Fe(CO)
1 3
1-.1,.1.-- .J ......... I--- 1 1 J
~—~I.-.-r.1..1--..1“.‘A‘i‘_:;4~;4~~- A--- .-
u n u 0,- mm u :10 “‘:l:“‘+.1o““{J
Figure 11. Nmr spectrum of 1-chloromethy1-Z-methylcyclo-
butadieneiron tricarbonyl 666 (CC14).
F'T Tv—Ir 'rrvvrfvv‘vr'v viiij:vr'1fvavv"v Y'fgvv'vfiv v'!:v:rvv y'lvfr'v ' I rvvf ' v
i. .L L. 1i & nm
”0

 

Br

 

 

 

Fe(CO)3

 

 

 

 

 

L A A A 4 A A_..L A l AAAAAAAAA l A A A A A 4 A A A A A J ..A AA A
k A 4‘ I A A A A A4. A A I L A A A l A A J A A _A A A I A A A A I A A A A I A A A A l A
u u on III! on. ':’ u no N no 0
I

 

Nmr spectrum of l-bromomethyl-Z-methylcyclo-

Figure 12.
butadieneiron tricarbonyl 666 (CC14).

66

 

 

 

Ifi r l v f W r J v I r r l r r r I J j v v v Lr r v ‘r I v v f1 L v v T rj v v v v 1
V V V V V V Vivi fi ff V V V V—fi VVVVVVVVVVVVVVVV V V V T 'fi r‘r #7
I: -L :& :i A "M
P”

‘ Fe(CO)

 

 

 

 

 

 

 

 

A l A A A A A AA A L A A A A AA A A A l A A A A A AA A _A A l A A A A A A A J A A A A A A A A A J
A.__ AA A A A A A I A A A A I A A A A l A A A A I A A A A l A A A A I A AA A J A A A A I .A
to u 0.0 0,0 "7:! 4.0 u a 0 Q .o o
..

 

Figure 13. Nmr spectrum of 1-(N,N-dimethyl amine)methy1-2-
methylcyclobutadieneiron tricarbonyl 66 (CDC13).

 

 

 

 

 

 

 

 

 

 

 

 

v vvvvvvvvvvvvvvv v v v ' Tffiv v vfiI : 'Y'V'Vvlf vv 7 VVV ! V V 7' T’I *
6L L g i 'L ON:
'9st DO.
(1) ‘C'H

(+)3 '

Fe(CO) CH3 :

p

t

r I

I

j I

C

I

I

i

LJLLAAAAAI-.Aii--..liA14.--Ailli..;--AAJ.1 11-1A J
A_LA LAAAl‘L‘ALAAALIALfAlAAAAI*AAAlAAAAJLAA‘lJ

" n -- ‘1'..:.'~.—.:' «. {1“}.- ... .

Figure 14. Nmr spectrum of 1-(+)-a-methoxy-a-trifluoromethyl-
a-phenylacetoxymethyl-2-methy1cyclobutadieneiron
tricarbonyl 66 from racemic 66 (CDC13).

67

1‘77 r fivvrlvvfifvrvV'If'fivvvvvflfi‘v'vvvv rv fo‘iV r

 

 

 

 

 

 

 

 

 

 

 

l
I
I
l
AJA‘L-A..iilA..i4A-iLJ AAAAAAAAA JAAAAA-14-AA
AAlLAAArAAAAAIAAAAIAAA‘IAAAAIAAAAAjAAALIA AA A
to m on 8,0 m QT 43 :0 ,-,-_ 2.0 no a

 

 

Figure 15. Nmr spectrum of 1-(+)-a-methoxy-a-trifluoromethyl-
a-phenylacetoxymethyl-2-methy1cyclobutadieneiron
tricarbonyl 12 from (-) Qg (CDC13).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

fifif j"'l‘"'ri"'Ifif"l""1"'rl"‘*IT'
1—*'-*v'1*'***1"."’r"."1 '
I“ 0.0 F a. U
o‘fs
o'é
(+)0
Fe CO
L
i
l . A Ali l L '. LJ L A l l
LALFAA L] ALILAAAI . IAAJALA IiAAj L I
M 7.. 0.. MMQOIM 8.. 3.. I. O

 

Figure 16. Nmr spectrum of 1-(+)-a-methoxy-a-trifluoromethyl-
a-phenylacetoxymethyl-2-methy1cyclobutadieneiron
tricarbonyl 1Q from (+) Q; (CDC13).

 

rvfrvivvvrvvvv[jvvafiivvvlufivvlvvvvlvvvvrvvwv~r

 

L L £ $ 1m
6 H H 0 no
H
N\¢

and Isomers

 

 

 

l A . l i . i I
._i A] . . . I . . . . I . . . . I . . . . 14A AJ . . . . I . I - . . .
no u u .‘n In I}! to l :0 n In 0

 

Hu—
.

 

Figure 17. Nmr spectrum of 3-methoxymethy1-4-methy1-8-
azatricyclo[4.3.0.02:5]nona-3-ene-7,9-dione-8-
phenyl §$ and isomers gé, g2 and gz (CDC13).

 

 

 

 

 

 

 

 

i
I

pdiLsgmers._

 

 

...“ .— .. ..---.

 

 

 

 

 

 

 

. 1.”;L1-.,, r -AAI ‘” I AAAI
lo 10 u up "FTP no. A u n «o a

 

Figure 18. Nmr spectrum of 3-methoxymethy1-4-methy1-8-
azatricyclo[4.3.0.02f5]nona-3-ene-7,9-dione-8-
phenyl g3 and isomers §§, fig and fix with Eu(hfbc)3
in CDCl,.

r—v—fiIwivvrjwrvvlrfifivrvvvavv

     
     
     

 

 

and Isomers

 

 

 

 

 

 

 

L A 1 l I . I l
._._AIA_...I...I“A.LAFL1.....I.1..I .-I-.._Li-
no 10.? m” H) 4.9 '0 . .w an L0 0

Figure 19. Nmr spectrum of 3- -methoxymethy1- 4- -methy1tricyclo-
[4.4. 0. O2 5]deca- 3, 8-diene- 7,10-dione §2 and
isomers 2Q, 21 and 2% in CDCl3

lfi-.l.-..
I

1 I ‘ I

 

 

 

 

Isomers I
. . I +1;
*‘f“‘““ .
I
I
I
I
I
I i :
I , .
I I
_ -.c__.4;.1-. '
Han—A. ,0 I In lug-$4-; -I ...—d— .- :_ A. t r J .n...l.. I

1 I: u

Figure 20. Nmr spectrum of 3- -methoxymethy1- -4- -methy1tricyclo-
[4. 4. 0. 02’5]deca- 3, 8-diene- 7,10-dione %& an and
isomers 3Q, 21 and 2% from racemic Q; th EUChbe)3

in CD

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7:! 'TTIZLT If? Eff ‘ ' If I c! 1' :1. '3 '- Jff'-!f£-if T
.L .L I; ah IL on
DD
and Isomers
1-A -.IAALLLI ......... 1-. I ...- -1 ........ 1 .._4 1 A J
1-TAA 11.1111L111A4I1.--l -I--1-T. -.I.
no u a. up "In u T no u u a
Figure 21. Nmr spectrum of 3-methoxymethy1-4-methy1tricyclo-
[4.4.0.0215]deca-3,8-diene-7,10-dione 82 and
isomers 3Q, 2 and 2% from 39% (+) Q% Wlth
EuChfbc)3 in DC13.
7' :III' 37 'AL' {ff CFIZc‘frCI ‘ '. L'JJJ!’ I if1 ' ‘ ' ' I '
L k L i ‘ VFW? I I”:
I no
0 H N
m N
CN
CN
and Isomers
I; II I
w, WWW
ilIIIJ.....1 ........ 11 ......... I I A JAA1 A111 4
AA1111A.J- , I 1.JA.A_I1 .l..-11A111AT1.AiI.
I. u I. If n.” ”I 0.0 1 33 ’0 0. I
Figure 22. NI: spectrum of 2,2,3,S-tetracyano-S-nethoxy-

methyl-6-methy1bicyclo[2.2.0]hex-S-ene

12 and
isomers 8Q, 81 and 82 (CDCl
N 'b'b NW

3)'

 

V—rV I r V V V I V V V "V LV V V r1 r Ti' 1 V V V V l V T V V I V V"'V V l V V V V

v 17V
'V jVVVVVVVVV VVV' Y
‘7‘Y‘Vr'vTIVVTVVVVVTLVVVV'V‘ l

 

 

CN
CN

 

 

 

 

 

 

1L. - ...... l 111111111 11 ........ J - . . - A- A l 1 A 1 I i
A AAA 1 A A A AT A LA A I A A A A l AAA—‘rATA I A A A A] A A A_I A A A A 1 A A AA A
0.0 2.. 0.. Up "a? 0.0,, u I. 0.0 0.

Figure 23. Nmr spectrum of 2,2,3,3-tetracyano-S-methoxymethyl-
6-methy1bicyclo[2.2.0]hex-S-ene lg (CDC13).

 

 

 

 

 

 

 

 

 

rfiVIVVVVLTVVVIV‘VVVIVVVVIVrV‘VJVjVVlTVVVrVVVV V
.K" "Ju TIIIIT J. """"" J. "' 8‘ Im
)0.

N

fl” CN + Eu(DMP)3
I N
CN
I y‘1 H

I 111111111 1-. A -1.1l1A1111AAJ 111111 AILA - 1 AAL
1-11.-1.11.,LIA4111111AI...11...-I---- --.-IA
no u u 3.0 my" a. u u 10 0

Figure 24. Nmr spectrum of 2,2,3,3-tetracyano-S-methoxymethyl-
6-meth{1bicyclo[2.2.0]hex-S-ene 12 with Eu(DMP)3
in CDC 3.

72

 

 

 

fl :1 is: :1; 5 72:44.22: ! :L' 15:11! r 1:2! :fxf
J. .1: .L I .T.
m
A H CN
fl. ‘N + Eu(hfbc)3
CN
J
] CN

 

 

 

 

 

 

 

 

AA A A A AA AA A J A A A A A A A A A I A A _A A A AA A A AJ A A AA A A A A AAJ A A A A AA A .L

L—A__Al A A A A j A A A A I A A A A A A A A I A A A A I A A A A A A AA 1 A_._A A A1

to 7.0 0.0 . m rfl u 3.. I. 1.0 O
.....rfil ‘

Figure 25. Nmr spectrum of 2,2,3,3-tetracyano-S-methoxymethyl-
6—methy1bicyclo[2.2.0]hex-S-ene 12 from racemic
Q; with Eu(hfbc)3 in CDC13.

rrvlvvrrjvvwv VTYVTWVWrIvvvVIVVVYIV‘W'VIf"*

vj—v—v
vlfifi fiva‘rfl vvvfifvijlfvivV'ffflj'i'vvvfiflvv

3
fl. E + Eu(hfbc)3
CN

 

 

 

 

 

 

 

 

 

1 AAA A A l AAAAAAAAA I A A A A A A AJ A A AA AA A l A l
A‘ A A A A A A l A A A A L A A A A A A A l A A A A I A A A l A ALL A
no 73 an 6.0 "an "F no :‘ u a. m u
U-

 

Figure 26. Nmr spectrum of 2,2,3,3-tetracyano-S-methoxymethyl-
6-methy1bicyclo[2.2.0]hex-S-ene Q3 from 46% (+)
Qg with Bu(hfbc)3 in CDC13.

 

Figure 27. Nmr spectrum of Z,2,3,3-tetracyano-5-methoxymethy1-
6-methy1bicyclo[2.2.0]hex-5-ene Z2 from 39% (-)
9% with Eu(hfbc)3 in CDC13.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

mug<mmnmm<

 

 

methoxymethyl-2-

methylcyclobutadieneiron tricarbonyl Q; (pentane).

CD spectrum of 52.5% (+) 1

Figure 28.

75

 

 

 

,. .HHHH...‘
...- 0‘
5.1..”
o1 '0 I .141.-. --.I QAt!
....IOCI
I. o.'.
~ 0 Ill. -
.i ‘6. .
.I' 1:1! Y. It'll 'W' ‘
. .
1| ['0 Y, I:
.. ‘19 z A .....
a A.
.0 I OIQIv ’1' II. A :-
c
‘. ‘ O in,
.
.....
‘ ‘I' L IIII It'll! ot'lllli
.

 

..,.1
III .I
. o u
iii. ill» u i
..o .
. . . A
.a . . ,
itt..lrv s. :91... or. I“
, .o .. .. ..
o. . . .
.. . o .. . q
lllll ix .1 ‘ I... II. | Vii. .... DID-...I' ii. II 0“ .l ‘6 uli. «I, .9 vjl,ll I. I!
. u . . . . . . . .
. . . . ..
. u A ., ,v . ,
1.... vo-u I . - I
m . .
. . ,
or .
'4’; pl. 1 -- I'O‘I

... Lillllo Illn .
7. - (J
0 tU ‘l 0

.
(i‘.

NUZ< . . me q

..z‘

‘; q\}

-2-

methoxymethyl

dieneiron tricarbonyl Q2 (pentane).

CD spectrum of 32.2% (-) 1

methylcyclobuta

Figure 29.

76

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

and isomers’
H3CHZOCH2CH3).

We

CD spectrum of 2,2,3.3-tetracyano-S-methoxymethyl-

6-methy1b1cyclo[2 2 0]hex-5-ene
fig, g;. and fig from 52.5% (+) 22

Figure 30.

77

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

and isomers
CHZOCHZCHS).

5-ene £3

tetracyano-S-methoxymethyl-

methylbicyclo[2.2.0]hex
gg, g; and fig from 32% (-) Q2 (C

CD spectrum of 2,2,3,3-

6

Figure 31.

78

 

  

    

. . o g ‘[
'.'1d I$°F¢?§?K”

 

:JRQNAI

AL

 

 

 

 

 

 

3 . . ' ' i : ‘ i. ‘ . I. L . '1 :. :.. .1 .
' I '. . , . .
A ‘-_ ' . 7 .
A -7 > :auu .250 3an m «an

Figure 32. CD spectrum of 3-methoxymethy1-4-methy1tricyclo-
[4.4.0.02’5]deca-3,8-diene-7,10-dione fig and
isomers 2Q, 3k and 22 from 52% (+) 22 H3CH20CH2CH3).

79

 

 

 

t Q In . a I . . ... . .
A W A .0 . . A
A . ' .
o . Q . . u .
A .. * . v- . . . .
1.! -vl Yl .lllol . A . v 'I :1 II o .A
r . o .Is _ - .
. A .. . _ . .
I o . fl . .
It -9: [III- II - I ll: 10%! Iv In O I. .... 8| ‘0‘..- l! II. .. XI. I!
u . . .
. A t .
A ‘ I n
o . A
..- - V O.
. a A
_ . 9A .A
. . D‘ ... .
no: &,o O A V» O... I .r.
o . II . . A
. . A . .
- . .- - --n ..- - -.A-
o . ., ...
. . . v
m _ _
.. .. II. A .. ol .4 7... A..
. . . . .
. . y .. ...... .
A. .. .
v 11.9 LO tInOIII 6|... 1; 11. illié. ulllltl§
. II. , . . .
. ... o . .
_. .o , . .
.0 4 a {:90 . . ‘9..I4~. -..:
. .. .
f .. 4 .
'D .. . . o I c
I! 9.3- 1-... Ionlo 0 .... . . oi i“! c
” .. “:1 ..I . . .. . . o
JAM . .I A. . .. .
_ . ..n 7 . .
Y‘. I .0 I... ill! 9' . u'l ‘|.|
w ... . u o U A . .
, . . O I. .. .
h .. ... .
II If: IIIIII 1 u.
o .. . . .
A v. .
. Q.\ ' u
. . o

 

 

 

\
..l '.
J

--

j

3
'mu...
I .'
l

v.

!

1:”?
I s
4-...--
r .
1 l
is“:
1.

i 2
3 z
1""
x

1

000 III II.

 

rl. ‘ ._ .
. .. . .
-..—...,-w§-q..-
.... - .. ...
. . .. ,
- -o -n‘ .
. .-

 

 

 

‘I‘l'l' 2" vI.

l’l'lix

 

wozmamomm<

 

 

lllllll

All)

ione-8-

-4-methy1-8~

]nona-3-ene-7,9-d
fié, gg and g1 from 50%

-methoxymethy1
02,5
isomers

4 d
ienéis)

azatr1cyc10[4.3.0.

CD spectrum of 3
phenyl
(+) 522

Figure 33.

80

Table 1. Mass Spectrum of 3-Methoxymethy1-4-methy1-
tricyclo[4.4.0.02:5]deca-3,8-diene-7,10-dione

83 and Isomers 2Q, 21,and 22

 

 

m/e Rel. Intensity m/e Rel. Intensity
218 1.0 91 ' 12.5
203 1.17 82 27.0
186 2.83 77 13.0
175 2.83 76 16.0
158 3.0 65 7.84
149 4.84 56 25.3
145 4.84 54 26.0
129 5.0 45 17.8
121 3.83 43 18.8
115 8.5 41 26.5
105 20.2 32 26.0
104 22.6 31 24.2
28 26.0

 

81

Table 2. Mass Spectrum of l-Methoxymethyl-2—methyl-
cis-3,4-carbonyldioxycyclobutene 61

 

 

m/e Rel. Intensity
126 1.0

112 2.58

95 2.54

83 2.37

65 1.27

45 1.0

 

82

Table 3. Mass Spectrum of l-Methoxymethyl-
2-methylcyclobutadieneiron Tricarbonyl 6%

 

 

m/e Rel Intensity
250 1.0
222 2.84
194 2.5
166 1.5
136 6.34
135 1.0
134 3.17
110 2.58
96 2.17
56 4.67

28 19.16

 

83

Table 4. Mass Spectrum of l-(NN-Dimethyl amine)methyl-
2-methylcyclobutadieneiron Tricarbonyl 62

 

 

m/e Rel. Intensity m/e Rel. Intensity
263 1.0 122 14.4
235 >22.2 121 10.7
219 1.14 110 15.1
207 >22.2 108 13.3
179 18.7 99 22.2
171 16.3 _ 95 20.2
151 >22.2 84 18.7
149 3.57 83 14.7
136 >22.2 65 4.87
134 >22.2 56 >ZZ.2

123 9.55 44 >ZZ.2

 

84

Table 5. Mass Spectrum of l-(+)a-Methoxy-a-trifluoromethy1-
a-phenylacetoxymethyl-2-methy1cyclobutadieneiron
Tricarbonyl 76

 

 

m/e Rel. Intensity m/e Rel. Intensity
452 1.0 ' 189 19.0
424 1.6 174 5.0
396 1.0 163 21.5
368 5.5 155 20.0
312 1.0 136 5.0
263 4.2 135 5.6
236 6.6 117 8.6
233 1.0 105 22.8
219 70.0 79 14.0
217 9.0 77 16.0

191 2.0

 

85

Table 6. Mass Spectrum of 2,2,3,3-Tetracyano-S-methoxymethyl-
6-methylbicyclo[2.2.0]hex-S-ene 79 and Isomers 80,

 

 

830' and 1%
m/e Rel. Intensity
238 1.0
223 1.38
206 1.12
179 2.25
173 2.63
141 1.75
110 2.5
109 2.5
95 7.38
77 1.88
76 2.0
67 6.0
51 3.38
45 4.0
31 11.2
28 19.4

 

86

Table 7. Mass Spectrum of 3-Methoxymethyl-4-mcthy1-
8-azatricyclo[4.3.0.02:5]nona-3-ene~7,9-dionc-
8-phenyl 84 and Isomers 85, 86,3nd 87

 

 

m/e Rel. Intensity m/e Rel. Intensity
283 1.0 132 0.675
268 4.25 127 0.432
255 0.405 121 4.2
240 0.216 119 2.16
222 0.243 105 4.05
199 0.243 104 3.78
184 0.378 91 3.97
174 0.945 77 3.64
171 0.838 65 1.65
163 0.189 45 3.11
149 0.433 41 2.18
136 3.14 39 1.95
135 3.02 32 2.62
28 4.18

 

..noo.o . ouauauua one mucuvnou uuuonauaaom

“onoauacoucon u ago novduwoaqnaxcogn-z a 2m:

.Amoo.o . ouuuauuu

“ocouxcuoocaxuuuuou - mzuha

 

 

e a
nwa n.v mun aw guano
A.. ca 80:884. am we use m.~. an v~ m~o.oa.v
Hwa A-v can MN youmo . u A . -
ROV NO Huavv<_ Wt MO hEG 0 cm 3 VGA Ohmc 0A V
x - an o.an as o.“ .m-.on.v
.no°.ofi-u am n.mn «2 cod .oou.oA-V .mmn.ofi.v .mma.en-v
.eoo.on-g an o.nn an mhd .aoa.on-v .oH~.oA-U .mnn.oA.v
.Ho.on-v on c.cn «a owv .mh~.cfi-v .nan.cfi-u .ma~.0n-v
. on m.~m as and .ond.°fi.g .va.OA.v .mha.ofi.v
.nco.ofi.v can °.mo as on .fiOH.On.V .n-.0n.v .~m~.ofi.u
.moo.cfi+v pzmz o.om as on” .oefi.0n.v .-~.ofi.v .mN~.oA.V
mm x mzua °.~n as h- .ONo.cfi-g .mNH.OA.U
x mzuu o.mn us ca“ .~h°.oH.v
..oo.oh-u mzup °.w~ as mad .oaa.ofl-v .Ho~.ofi.v .mnn.0n-v
x mzua ”.04
x mzua ”.0. «a n- .4mm.ofi.2
ouwwofiwwowm.mweo x mzuy m.~m as mm. .on~.ofi.v .¢m~.°n.v .A-.oA.U
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