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dissertation entitled

The Synthesis of Polythienyls and Their
Incorporation into Large Ring Macrocycles

presented by

Thungmei H. Luo

has been accepted towards fulfillment
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Ph. D Chemistry

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THE SYNTHESIS OF POLYTHIENYLS AND THEIR INCORPORATION

INTO LARGE RING MACROCYCLES

By

Thungmei H. Luo

A DISSERTATION
submitted to
Michigan State University
in partial fulfillment of the requirement
for the degree of
DOCTOR OF PHILOSOPHY

Department of Chemistry

1987

ABSTRACT

THE SYNTHESIS OF POLYTHIENYLS AND THEIR INCORPORATION

INTO LARGE RING MACROCYCLES
By

Thungmei H. Luo

The synthesis or various individual unsubstituted and
substituted linear polythienyls and their conversion to the
macrocyclic polythienyls have been investigated. Michael
addition of thiophene carboxaldehydes to Mannich base as
well as vinyl sulfone gave a variety of symmetrical or
unsymmetrical, substituted or unsubstituted 1,4-diones.
Cyclization of 1,4-diones with Lawesson's reagent led to a
series of linear polythienyls containing both odd and gygn
numbers of thiophenes. Thus the syntheses of a-ter-, a-qua-
ter-, a-quinque-, a-sexi-, 1,12-dibromo-a-quinque-, 3',4'-
dimethyl-a-quinquethieny1, and zgs-bis-(3",4"-dimethy1-
2',2"-5",2"'-terthienyl)-thiophene were accomplished.

Coupling reaction of bromothiophenes by low valent
nickel provided a convenient way to prepare the gxgn number
of polythienyls: 5,5'-diformyl-2,2'-bithienyl, l,10'-
diformyl-a-quaterthienyl, a-sexithienyl, and 5,5'-bis(3"i4"-
dimethyl-Z",2"'-bithienyl)-2,2'-bithieny1.

Thunmei H. Luo

Condensation of a-bi-, a-ter—, and a-quaterthienyl

with benzaldehyde or anisaldehyde with Lewis acids yielded
mixtures of macrocyclic oligomers.

Cyclization of linear polythienyls to the macrocyclic

polythienyls, in which all the thienyl rings are connected

together in a cyclic manner, were not fruitful due to the

insolubility of either starting materials or products.

To My Parents

ACKNO“IEDGEMENTS

I wish to express my sincere appreciation to Professor
Eugene LeGoff for his enthusiasm, encouragement and
guidance throughout the course of this study.

Appreciation is extended to the departement of
chemistry at Michigan State University for financial support
in the form of teaching and research assistantships, and
Professor Eugene LeGoff for research support at varios times
during this period.

A special thanks goes to my husband, Jihmei, without
his love, companionship, and encouragement this work could
never have been done. Many thanks go to our family,
for their love, understanding, and support over the past few

years.

ii

TABLE OF CONTENTS

Chapter page
LIST OF TABLE O O O O O O O O O O O 0 O 0 O O O O O 0
LIST OF SCHEMES O O O O O O O O O O O O O O O O O O 0 . Vii

LIST OF FIGURES O O O O O O O O O O O O O O O O O O

. . ix
INTRODUCTION O O O O O O O O O O O O O O O O O O O O O O 1
RESULTS AND DISCUSSION. . . . . . . . . . . . . . . . . 11

A. Synthesis of various unsubstituted and

substituted linear polythienyls . . . . . . . . 12
B. Syntheisi of novel macrocyclic polythienyls

I. Snythesis of 12 type macrocyclic polythienyl . 25

II. Attempted synthesis of 11 type macrocyclic

polythienyls . . . . . . . . . . . . . . . . 30

C. Conclusions . . . . . . . . . . . . . . . . . . 32
EXPERIMENTAL

General Procedure . . . . . . . . . . . . . . . . . 34
5-Pormyl-2,2'-bithienyl (30a) . . . . . . . . . . . 34
5-Formy1-2,2'-S' ,2"-terthienyl (30b) . . . . . . . . 35
3-Dimethylamino-l-(2-thienyl)-propanone 6H1) . . . 35
3-Dimethy1amino-l-(2-2'-bithienyl)-propanone cub). 36
l-(2-Thienyl)-4-(5-2,2'-bithienyl)-1,4-
butanedione (32b) . . . . . . . . . . . . . . . . . 37
l,4-Bis-(5-2,2'-bithienyl)—1,4-butanedione (32c) . . 37
1-(5-2,2'-bithienyl)-4-(5-2,2'-5',2"-terthieny1)-
1,4-butanedione (32d) . . . . . . . . . . . . . . . 38
5,5'-Diformy1-2,2'-bithienyl (35b) . . . . . . . . i 39

iii

Chapter page
5,5'-Diformyl-2,2'-5',2"-terthienyl (35c) . . . . . 4o
thiophene (36a) . . . . . . . . . . . . . . . . . . 4o
5,5'-Bis[4-(2-thieny1)-1,4-butanedione]-2,2'-
bithienyl (36b) . . . . . . . . . . . . . . . . . . 41
S-Bromo-5'-formyl-2,2'-bitheny1 (38). . . . . . . . 42
1,4-Bis-(2-bromo-5-thienyl)-l,4-butanedione (39). . 42
1,4-Bis-(5-bromo-5'-2,2'-bithienyl)-l,4-
butanedione (40) . . . . . . . . . . . . . . . . . 43

1,4-Bis—(5-formyl-5'-2,2'-bithienyl)-l,4-

butanedione (41) . . . . . . . . . . . . . . . . . 43
a-Quaterthienyl (14). . . . . . . . . . . . . . . . 44
a-Quinquethienyl (15) . . . . . . . . . . . . . . . 44
a-Sexithienyl (l6) . . . . . . . . . . . . . . . . 45
5,5"-Dibromo-2,2',5',2"-terthienyl (42) . . . . . . 45
1,12-Dibromo-a-quinquethienyl (43) . . . . . . . . 46
S-Bromo-2,2'-5',2"-terthienyl (45) . . . . . . . . 46
Coupling of 44 to 5,5'-diformyl-2,2'-

bithienyl (35b) . . . . . . . . . . . . . . . . . . 46
Coupling of 38 to l,lO'-diformyl-a-

quaterthienyl (47) . . . . . . . . . . . . . . . . 47
Coupling of 45 to a-sexithienyl (l6) . . . . . . . 48
1,4-Bis-(2-thienyl)-2,3-dimethy1-1,4-

butanedione (49) . . . . . . . . . . . . 48
3 ' , 4 ' -Dimethyl-2 , 2 '-5' , 2"-terthienyl (50) 49

iv

Chapter page
5-F0rmy1—3',4'-dimethyl-2,2'-5',2"—
terthienyl (s3) . . . . . . . . . . . . . . . . . . 50
l-(2-Thienyl)-4-(3',4'-dimethyl-2,2'-5',2"-
terthienyl)-l,4-butanedione (54). . . . . . . . . . 51
3',4'-Dimethyl-OL~quinquethienyl (55) . . . . . . . 51
1,4-Bis-(3',4'-dimethy1-2,2'-5',2"-terthienyl)-
1,4-butanedione (S6). . . . . . . . . . . . . . . . 52
2,5-Bis-(3",4"-dimethyl-2',2"-5",2'"-terthienyl)
-thiophene (57) . . . . . . . . . . . . . . . . . . 52
5-Bromo-3 ' , 4 ' -dimethyl-2 , 2 ' -5 ' -2 "-terthienyl (58)
and 5,5-dibromo-3',4'-dimethyl-2,2'-5'-2"-
terthienyl (74) . . . . . . . . . . . . . . . . . . 53

Coupling of 58 to 5 , 5 ' -bis (3 " , 4"-dimethyl-

2",2"'-bithenyl)-2,2'-bithieny1 (59) . . . . . . . 53
Cyclization of 13 with 62 (64a). . . . . . . . . . 54
Cyclization of 13 with 63 (64b) . . . . . . . . . . 55
Cyclization of 10 with 62 (64c) . . . . . . . . . . 55
Cyclization of 13 with 63 (64d) . . . . . . . . . . 56
Cyclization of 14 with 62 (64c) . . . . . . . . . . 56
Cyclization of 14 with 63 (641’) . . . . . . . . . . 57
l,4-Bis(2,2-dithienylmethane)-1,4-diketone (73) . . 57
l,lO-Dibromo-a-quaterthienyl (75). . . . . . . . . 58

APPENDIX. . . . . . . . . . . . . . . . . . . . . . . . 59

BIBOGRAPHY. . . . . . . . . . . . . . . . . . . . . . . 77

5.

6.

LIST OF TABLES

1,4-Diketones from Aldehyde and Mannich base .
Polythienyls by Ring closure of 1,4-Diketones.
Color and UV Spectrum Data (the highest JKmax

value) of a-Polythienyls . . . . . . . . . .

1,4-Diketones from Aldehyde and Divinyl Sulfone

1H-NMR Spectra of 64 . . . . . .

13C-NMR Spectra of 64 . . . . . . . . . .

Coupling of Various Polythienyl Dibromide . . .

vi

page
15

17

18
19
27
28

31

Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme
Scheme

Scheme

10
11
12
13
14
15
16
17
18
19
20
21
22
23

24

LIST OF

vii

SCHEMES

13

14

14

16

16

18

20

21

22

23

24

25

25

26

26

29

Scheme
Scheme
Scheme
Scheme

Scheme

25
26
27

28

viii

page
29
30
30

31

LIST OF FIGURES

Figure

1.

10.

11.

250 MHz 1

2 , 2 ' -bithieny1) -l , 4-butanedione (32b) .

1

250 MHz H NMR spectrum of

bithienyl)-1,4-butanedione (32c) .

1

250 MHz H NMR spectrum of

5',2"-terthieny1(50). . . . . . .

1H NMR spectrum of

250 MHz
2,2'-5',2"-terthienyl (53). . . . .
250 MHz 1H NMR spectrum of
dimethy1-2,2'-5',2"-terthienyl .

250 MHz 1

1,4-bis-(5-2,2'-

H NMR spectrum of 1-(2-thienyl)-4-(5-

3',4'-dimethyl-2,2'-

5,5'-diformyl-3',4'-

H NMR spectrum of l-(2-thienyl)-4-(3',4'-

page

5-formyl-3',4'-dimethy1-

dimethyl-z , 2 ' -5' , 2 "-terthienyl) -l , 4-butanedione (S4) .

250 MHz 1

quinquethienyl (55) . . . . . . . .

250 MHz 1

2 , 2 ' -5 ' , 2 "-terthienyl) - 1 , 4-butanedione (56) .

250 MHz 1

2' , 2"-5" , 2 ' "-terthienyl) thiophene (57) .

250 MHz 1

2,2'-5'-2"-terthieny1(58) . . . .
250 MHz 1

dimethyl-Z , 2 ' -5 ' -2 "-terthienyl (74)

ix

H NMR spectrum of 3',4'-dimethyl-cz-

H NMR spectrum of 5,5-dibromo-3',4'-

H NMR spectrum of 5-bromo-3',4'-dimethyl-

H NMR spectrum of l,4-bis-(3',4'-dimethyl-

H NMR spectrum of 2,5-bis-(3",4"-dimethyl-

59

60

61

62

63

64

65

66

67

68

69

Figure

12.

13.
14.
15.
16.
17.

18.

250
250
250
250
250
250

250

dithienylmethane)-1,4-diketone (73) .

MHZ

MHZ

MHZ

MHZ

MHZ

MHZ

MHZ

NMR

NMR

spectrum
spectrum
spectrum
spectrum
spectrum
spectrum

spectrum

of
of
of
of
of
of
of

(64a) .
(64b) .
(64c) .
(64d) .
(64¢) .
(64f) .

1,4-bis(2,2-

page

INTRODUCTION

In accord with the Hfickel rule,1 planar monocyclic
conjugated systems containing 4n+2 r-electrons (n-o, l, 2,
3, ....) are considered aromatic. This concept remains
valid for polynuclear condensed systems if the Huckel number
of w-electrons are located in peripheral atomic orbitals. In
principle, the formation of an aromatic w-electron ensemble
may occur due to the p-orbitals not only of carbon atoms but
of other atoms as well. Thus, in addition to such carbo-
cyclic compounds as benzene and naphthalene, an extensive
class of heteroaromatic structure exists.

Macrocyclic systems hold great interest in the
chemistry of heteroaromatic compounds. Such compounds
include porphins 1, which have an aromatic 1r-electron system
of the [18] annulene type. Like annulenes, they exhibit a
diamagnetic ring current in the 1H-NMR spectrum, which

serves as a qualitative criterion for aromatic character. In

 

 

addition, several expanded porphrin molecule have been

2

reported, such as hetero [22] annulene platyrin 2 and

3 Indeed, the recent

hetero [26] annulene platyrin 3.
synthesis of hetero [18] annulene porphycene 44 has caused a
great deal of excitement since it is a structure isomer of
porphyrin. However, though porphyrins system has been
studied since the turn of the century, only a few reports
has been conducted on the sulphur analogues. [18] Annulene
trisulfide 5 has been synthesized by cyclocondensation of
thiophene-2,5-diacetic acid 6 and methyl cis-a,fi-bis(5-

formyl-z-thienyl)-acrylate 7 under standard Perkin's'
reaction conditions followed by hydrolysis and

5'6 All

decarboxylation of the product (Scheme 1).
experimental evidence supported the fact that 5 is a
nonplanar, nonaromatic system in which the aromatic

thiophene subunits are bridged by olefinic vinylene groups.5

Scheme 1

(XhMe

 

Although pyrrole and furan reacted with acetone and

7,8,9

hydrochloric acid to generate porphyrinogen and

tetraoxaquaterenelo'11

respectively, initial attempts to
prepare tetrathiaquaterene 9 in an analogous manner failed.
However, under more vigorous reaction conditions (thiophene,

2 the residue was shown to

acetone, and 72% sulfuric acid),1
contain the desired macrocycle 913 (Scheme 2).

A number of thiophene oligomers and their derivatives
have recently stimulated much attraction. A great deal of
the interest in this system results from their wide range of

4

photobiological effects.1 Most notably, they are toxic to

nematodes, and this effect can be greatly enhanced by the

Scheme 2

CH3 CH3
4 g \) + 4 \ c / 72% sto,
3 ll '

presence of ultraviolet light.15 The most carefully
scrutinized of these compound is alpha-terthienyl 10.16 In
addition, polythiophene is among the most widely studied
organic materials that can be conduct electricity.17'18
Thus, several novel macrocycles which contain the
polythiophene units has been designated to make, such as 11

and 12 type cyclophanes. Apart from questions regarding

 

5
aromaticity a second point of interest here comes from the

conductivity of 10 analogues.

Alpha-terthienyl 10 was isolated from Tagestes

19

plants and has now been made by many different routes. It

was originally synthesized by reacting Z-iodothiophene with
copper, a procedure which gives a complex mixture of
products, from which the oligomers possessing 2 to 7
thiophene rings could be obtained individually in low yields

20,21

after tedious purification steps. Related reactions

in which two different iodothiophenes were reacted with
copper also produced complex mixtures.22

Even the biologically active alpha-terthienyl 10 was
synthesized in good yield with reactions which did not
produce any of the related oligomers, namely the cyclization
of 1,4-di(2'-thienyl)-l,4-butanedione with hydrogen sul-

23,24

fide, or that of 1,4-di(2f—thienyl)-l,3-butadiyne with

25,26 27 The

sodium sulfide, or a modified Wittig reaction.
synthesis of the other individual alpha-thiophene had not
received the same attention until 1983.

In 1983, Kagan reported three synthetic routes to the
individual alpha-thiophene oligomers. The first approach
involved the oxidation of the alpha-lithio derivative with
cupric chloride to obtain alpha-thiophene oligomers

8 Scheme 3

containing an gygn nummber of thiophene rings.2
is illustrated with the synthesis of 2,2'-bithienyl 13, C!-
quaterthienyl 14, and.cx-sexithieny116 in 83, 85 and 73%

conversion yields (but the actual yields are low) from

will]? ”ll-[31]?“ 932—" WW3:

thiophene, 2,2'-bithienyl 13, and a-terthienyl 10
respectively. The second approach, leading to oligomers
containing from 2 to 6 thiophene units attached by their 2
and 5 positions in moderate yield, involved the iodine
oxidation of a suitable complex obtained by stepwise
reactions of 9-BBN with methanol, a 2-lithiothiophene, boron

29 The

trifluoride etherate, and a second 2-lithiothiophene.
reaction sequence is outlined in Scheme 4. The third
approach provided various individual oligomers possessing
either odd or even number of thiophene rings from the Glaser
symmetrical coupling of thienylacetylenes (Scheme 5) or the
Cadiot-Chodkiewicz unsymmetrical coupling (Scheme 6)
following the cyclization of 1,3-butadiyne unit into
thiophene with sodium sulfide.30
Kagan has reported the formation of‘ a-quinquethienyl
15,¢1-septithienyl 17 and a-quaterthienyl 14 in moderate to
excellent yield ma the above synthetic route. However, the
a-sexithienyl 16 analog was not mentioned. In addition, the
yield of a-quinquethienyl 15 by the same method was not
reproducible, only 21% overall yield from dibromide 18, by

Tasaka and his coworkers.17

 

 

 

 

 

Scheme 4
:B— (MWe; B S p -—————>» B
R/ TENWe R/' S P
Li
1
/S\ i R\-- / \ PH '2 / \
R .+ +1 n
U \ / n=p+q
sq
p q n yield °/o(based on LDA)
1 1 2 80
2 2 4 48
1 3 4 50
2 3 5 55
1 4 5 53
3 3 6 45
2 4 6 59
Scheme 5

[Q] —» [man—~[Q]—»

2n+1

1 2O n=2 15

”:3 1 7

[Q] .1... {IN-owe [Q] M [I Q]

20.
n-2 72.7% 73.5% 1 5
n-3 98.5% 97.5% 1 7

 

 

Scheme 6

U I: / \] 1) CuZCIz. NHZOHHCI. 70% ethyl amine
S C‘C'Bl’ + H- S 3% 2) NaCN V
22 23 95.6%

N S

Qm—[Q]-~ 32 A [Q]

S s 2 100% S 4
24 14

Tasaka and his coworkers also has reported the
formation of a-quinquethienyl 15 in better yield via the
coupling of thiophene-z-magnesium bromide with dibromide 25

by nickel chloride complex (Scheme 7).17

Scheme 7

 

QQQ "WA. Q xx xx
- ° B
s s s Bra. 780 r s s s r _,
61%
10 25

+

[3— MgBr

 

 

ll

(thPCHZCHzPthmiCIa
H.[ / \]_ H
83% 5

S
15

9
Finally, a very recent paper reported four-steps

sequence to a-quinque- 15 and a—septithienyls 17 from a-bi-

 

13 and a-terthiophenes 10, respectively (Scheme 8).31
Scheme 8
[Q] W [I \] .0... ——-
_ _ 1 H- _
H s n” AIC|3IC82 S n Was/H20
n=2 35% n=2 98%
nAB 68% n=3 93%
[I \] [Q] [I \] s [I \]~
(:3: cm. s [E )- s n
8
=2 60%
28

 

Rilomc'z: H|:/Q;Ln+1+ Hm

15 n=2 56%

U

S

1 7 I133 380/0 2 9 "33 20/0

LR- Lawesson's reagent

This procedure is limited to the formation of egg number of
thiophene rings and the overall yields are generally quite
low.-

Explored in this thesis are the application of linear
polythienyls in the synthesis of large ring macrocyclic
polythienyls. This work is presented in two sections,
describing, a) the synthesis of various unsubstituted and

substituted linear polythienyls and b) the utility of the

10
precursors in condensations leading to novel macrocyclic

polythienyls.

11

RESULTS AND DISCUSSION

Due to their potential applications as organic
conductors, molecules with large conjugated cyclic r-systems
such as 11 and 12 are of great interest. As a class
compound such as 11, in which all the thiophene rings are

linked together in a cyclic manner, will have 4n electrons

 

which provides an opportunity to determine whether they
exhibit localized aromaticity in the component heterocyclic-

nuclei or cyclic delocalization to give an antiaromatic

annulene. Theoretical calculations32

33,34

and experimental
results have shown that (4n+2) annulenes will only be
aromatic up to and including [22]annulene while [26]annulene
(n86) is no longer be aromatic. However, inspection of the

molecular model of 12 showed that the macrocycle is rigid

12
and planar. Thus it may lead to cyclic delocalization and a

peripheral diamagnetic ring current.

Retroanalysis of 11 and 12 suggests the necessary of
linear polythienyls. As mentioned in the introduction, the
methods for the synthesis of linear polythienyls reported in
literature are not very efficient. Thus, several new

approaches were examined.

A. Synthesis of various unsubstituted and substituted linear polythienyls

Four different approaches to the unsubstituted and
substituted linear polythienyls have been investigated.
Their net transformations are summarized in Scheme 9. The
first approach (eq. 1) provides various polytheniyls
containing odd or even number of thiophenes resulted from
the Michael addition of aldehydes to Mannich base, followed
by the cyclization of resulting 1,4-diketones with
Lawssson's reagents. The second approach (eq. 2), leading
to polythienyls containing odd number of thiophenes,
involves the Michael addition of aldehydes to vinyl sulfone,
followed by the cyclization of 1,4-diketones. The third
approach (eq. 3) engages the coupling reaction of'
bromothiophenes by nickel and reducing metals, which proves
to be useful in the preparation of polythienyls containing
even number of thiophenes. The fourth approach (eq. 4)
provides 3',4'-dialkyl-polythienyls (i.e. 3',4'-dimethyl-
2,2'-5',2"-terthienyl) from the oxidation of the lithium

enolate of 2-propionythiophene with cupric chloride,

13
Scheme9

0 0 \
s N\ s H 3 oo 3
Iawesson'sreagent /
t R S Re

 

 

 

 

S S
0
2 / \ \
R—w + AsoA —. R
s H 2 5 oo 3 R
Lawessonsreagent : R I / \ \ R
S S S
mmurvm
a Q A QQ
R R R
s 33' ZLDMMZ S S
° W W RQQQ
4
11% S 00 S R
Lawesson'sreagent ‘
3 R \ / \ R
S S S
s
I

Lewesson's reagent : CH’O—O— P< :)1; 0-004,
8

followed by the ring closure reaction.

The Michael addition of aldehydes to Mannich base in
the presence of cyanide as catalyst can be performed in good

35-37 which provides a

yields by the Stetter's procedure,
convenient method for preparing 1,4-diketones as shown in
Scheme 10. In each case the necessary aldehyde 30 . was

synthesized from a simpler thiophene precursor, which was

14

 

Sdmmwlo
[Q]--I [QAA QQQ
30 31 32

formylated with N-methyl-N-phenylformamide in the presence

8 Two Mannich bases.(3la, n-l; 31b, n-Z) were

of poc13.3
synthesized from the reaction of 2-acetylthiophene or 2-
acetylbithienyl with paraformaldehyde, dimethylamine

hydrochloride and concentrated hydrochloride in ethanol
solution.39

Attempts at nucleophilic substitution of 5,5'-di-
acetylbithienyl 33 with Mannich reagent under a variety of
conditions failed to give the desired.34 (di-Mannichbase of

bithienyl), despite the fact that a similar mononucleo-

 

 

Sdmmell
QQJ’I um I°I W ~W ,
S S / Cl +O\’O 95%ethanolr S S Nx'HCI
7&3%
O 0 O
W \ [Wm-“0AM III
+2 NH-HC] + 0 A 8mm
8 S / 0V 95%ethanol
33
3 HC=N+(CH3)Br' CHCI’ O O
3 + 2 2 HC] WNCHCI
693%
+
o o
\
HCI'INWNtHCI

15
philic substitution of 5-acetylbithienyl could be carried

out in good yield (Scheme 11).

The aldehyde 30 reacted with Mannich base 31 in dry
DMF in the presence of KCN at room temperature to give 1,4-
diketone 32 in good yield. Table 1 (entry 1-5) lists

several diketones prepared by this method. The bis-

Table 1 1,4-Diketones from Aldehyde and Mannich base

 

 

entry no. 1.4-diketone yield(%) mp. (°C)
1. / \ / 70 132-133
s 00 s
323 (m, n=1)
2. z 3 4 3 Z/ \5 z 3 ' 85 1635-1645
s ()0 s s
32b (m=1, n=2)
3. [\3 ["34 Egg 93
s s 00 3

32b 0n=2.n=1)

4. l§z§< >[ \5!) 87 225-226

S S 0 O S S
32¢ (m=2, n=2)
5. W 95 2275-2295
S S S 0 0 S 5
32d On=3.n=2)
6- / \ / \ / \ 69 186-1875
s o S O O S
36a (p=1)

r’

/ \ / \ / \ I \ 69 256-257
S

s 00 s 01) s
36b (p=2)

 

16]
aldehyde 35 ‘was also allowed to react with 3-dimethylamino-

l-(2-thienyl)-propanone 31a to give bis-1,4-diketone 36 in

'good yield as indicated by entries 6-7 in Table 1 (Scheme

12).
Sdmnnlz
() (3 ()
Hg-m;A-m S N. m AWE [01m

35 31a

All the structures of diketones were confirmed by
their spectra. The 1H-NMR spectrum of methylene protons
appeared at 2>3.37-3.40 and thienyl protons at 8 7.05-7.90.
Low solubility of 3211 prevented us from obtaining its NMR
spectrum. The IR absorptions in the range of 1637-1650 cm-1
were obtained for the.a,B-unsaturated ketones.

These 1,4-diketones readily give the polythienyls upon
treatment with Lawesson's reagent in toluene (Scheme 13).40

Oligomers possessing three, four, five, and six thiophene

 

Sdmmel3
'WWCXJ: H ”“32: ”W = ”[09:38
32

 

h

QQQQQ “82:?” H {[1331

P
36

17
rings were prepared in this manner in excellent yields

(Table 2). Their color and UV spectrum data are summarized

Table 2 Polythienyls by Ring closure of 1,4-Diketones

 

entry no. 1,4-diketone polythienyl yield(%)

 

I m [[0]- ..
s 00 s S 3
32a 10
2.
s o<) s s s 4
32b 14
s s 00 s s s S 94
32c 15
I- W [0]
n- -H
s s 8 CC) s s S 6 86
32d 16
5- H-m-H
s o S ()() s s 5 91
36a 15
s oc> s s o o s. s 6
36b 16

 

in Table 3. The color apparently deepens upon going from a-
bithienyl to a-sexithienyl. This is the result of the fact
that an increas of the number of thienyl rings in the mole-
cule shifts the position of the main maximum to longer wave

length.

18

Table 3 Color and UV Spectrum Data (the highest )“m value) of (Jr-Polythienyls

S

 

 

n 2 3 4 5 6
color colorless pale yellow orange yellow orange red
ACHQ3 307 64 4

rnax Gun) 3 392 16 . 434

 

Individual a-polythienyls can be synthesized in great-
ly improved yields over the traditional methods by construc-
ting a 1,4-diketone properly substituted with thienyl groups
and treating it with Lawesson's reagent. The procedure is
versatile enough to allow the synthesis of oligomers having

either an odd or an even number of repeating units.

The thiazolium salt catalyzed addition of divinyl
sulfone to thienyl aldehydes provides another route to make
1,4-diketones (Scheme 14). This procedure is an extension
of the Michael-Stetter addition described by Stetter, which
have been useful in the preparation of several symmetrical

41, 42

1,4-diketones. The divinyl sulfone was added dropwise

Sdmmml4

O .
dumbh gm;
R—WH + Asoz/u. NaOAcum =R / \ \ R

S amemmml S ()0 S

 

- 19
to a hot solution of thienyl aldehyde, thiazolium salt and

sodium acetate in ethanol. After the mixture was stirred
overnight, the desired 1,4-diketone was collected in fair to
good yields (Table 4). The yields of these reactions herein
described are not better than that of aldehydes with
Mannich base as described in Scheme 10. However, it is a
one-step facile reaction for the synthesis of 5,5'-
disubstituted-l,4-diketones, which are precursors of 5,5"-

disubstituted-polythienyls.

Table 4 1,4-Diketones from Aldehyde and Divinyl Sulfone

 

 

nmwwm: lAqfihmxw fidd mpJRD
9 48 132133
/ \ CH / \ /
5 s 00 5
30a 32a
('9 65 225 226
we]! / \ / \
S S s s 00 s 5
30b 32c
/\ 9 /\ /\ 20 175176
Br S CH 1' S 00 S r
37 39
O
Btu-[W514 Br / / \ B, 45 225<dec.)
S S s s cc) 5 s
33 4o
0 Q 0 O
nI-Q-QI- III-WI- I
S S s s 00 s s

 

20
These 1,4-diketones (except 41) readily give the

polythienyls upon treatment with Lawesson's reagent in dry
toluene under reflux temperature in good yields.40 The
cyclization of 32a and. 32c to the corresponding

polythienyls, a-ter- and a-quiquethienyl has been described

earlier (see Table 2). Scheme 15 summarizes the results of

5,5'-dibromo-1,4-diketones to 5,5"-dibromopolythienyls.

 

 

Sdmnels
Lawesson's rea ent
s ()0 S tobam S S S
Lawesson's reagent
Br / / \ Br :
S S t) s s tflggf
40
S S S S S

In conclusion, a simple method is available for the
synthesis of unsubstituted and disubstituted linear <1-
polythienyls,- where individual members may be obtained in
good yield. However, the method herein described is limited
to the synthesis oftx-polythienyls with an ggg_ number of

thiophene units.

A recent report of the facile coupling reaction of

chloroarenes by nickel and reducing metals to give the

3

corresponding biaryls4 prompted a similar study with 5'-

21
bromo-a-polythienyls to yield the a-polythienyls having even

number of thiophene units. Only three reactions of mono-

'bromothienyls are summarized in Scheme 16, the further study

 

 

 

Scheme 16
o o o
u bmmgzmpng _f IL4[_}¥lri§-"
Br /8\ CH DMAC, 51% A HC S S CH
44 35b
/ \ / \ (I? NiCl 211.9911 0 \ C")
2. 3 ¥ "
Br'Q‘Q'CH DMAc, 50.7% ' HC IS Is /8\ /S\ CH
33 47
/ \ / \ NiC12,Zn,PPh3 : \ / \ \ / \
mm. DMAC, 54% 5 s s 16 s s s
45

will be discussed in later section. Both of 38 and.45 (44

is commercial available) were synthesized by bromination of
a simpler thiophene precursors with pyridinium perbromide
in chloroform. The nickel catalyst was generated in situ
from anhydrous nickel chloride, triphenylphosphine, and
excess zinc in a dry, dipolar aprotic solvent DMAC(N,N-
dimethylacetamide) at 60-80°C under Ar atmosphere. To zero-
valent nickel reagent was added neat( or solid)
bromothienyls. The mixture was heated at 80°C for 16 hrs.
Work up of the resulting mixture gave the desire

polythienyls in good yield.

The generality of the reactions for making the higher

polythienyls is severely limited by practical considerations

22
of solubility, which decreases rapidly as the oligomers

increases. To avoid the solubility problem, the synthesis
of polythenienyls substituted in 3- and 4-posi-tions have
been investigated.

The introduction of methyl substituents into the 3'-
and 4' positions of thecfi-terthienyl can be achieved by

44 which involves oxidation of the lithium

Kagan's procedure,
enolate of z-propylthiophene 48 with cupric chloride
followed by cyclization of 1,4-diketone 49 with Lawesson's

reagent (Scheme 17).

Sdmnsl7

*
W“ 1) lDA / ‘ Lawesson's
2) cm2 (55—20 OS—[S>—'magemfl[ 831915)

18.4% 49 76.6%
WM [111231111
3 s ”(mcb s s ()0 s s

51 52

Two diastereomers of 1,4-bis-(2-thienyl)-2,3-dimethyl-
1,4-butanedione 49 were separated by flash column

lH-NMR (5 l.33(31-1,

chromatography, and identified by their
(1), 3.75(lH, m), 7.12(1H, dd), 7.60(ll-I, dd), 7.79(lH, dd)
and 1.18(3H, d), 3.77(lH, m), 7.16(lH, dd), 7.69(lH, dd),
7.84(1H, dd)).

Further extension of Kagan's method was not realized

since attempts to make 52 from 5-propionyl-2,2'-bithienyl 51

23
under similar condition resulted in the recovery of starting

material (Scheme 17).
Formylation of 50 Ito 5-formyl-3',4'-dimethyl-2,2'-

4 with

5,2"-terthienyl 53 followed by Michael addition3
Mannich base 31: provided 1,4-diketone 54. The usual
cyclization of 1,4-diketone 54twith LR(Lawesson's reagent)40
to 55‘was accomplished in excellent yields (Scheme 18). The

structure of orange-yellow solid. 55 ‘was obvious from its

 

 

 

 

 

Sdmmnl8
0
ll
HC- "(2113 o
[/\§2/\§[/§ t \/\/\('}H —‘[
s s s Foch s s s
50 52.6% 53 KCN
+ DMF
/ \ O
CWN< ——
31a
W Wat-DWI \ \I
S 5 Ms S S S S S
68% S 54 00 S 83% 55

spectra. The 1H-NMR spectrum contained two three-proton
singlets at g 2.24 and 2.27 for the methyl groups and ten--
proton multiplet at 5 6.94-7.26 for the thienyl protons. The
mass spectrum of 55 showed a strong molecular ion peak at
m/e 440. A long wavelength absorption of UV spectrum is at
400 nm.

The 1,4-bis-(3',4'-dimethyl-2,,2'-5',2"-terthienyl)-

. 24
1,4-butanedione 56 was prepared from readily available

aldehyde 53, by Michael addition with divinyl sulfone
(Scheme 19).41 The 1,4-dione 56 then readily gave 2,5-bis-
(3",4"-dimethyl-2',2"-5,2"'-terthienyl)-thiophene 57 upon
usual treatment with Lawesson's reagent in toluene. The 1H-

NMR spectrum of orange solid 57 showed two three-proton

 

Sdmmn19

/\/\/\(") thiaz°“““”“‘"A/\/ /\ I\/\/\

s s s CH4Mé\&%Z§ :gfiggn s s; s 00 s s s
53 60% 56

Lawesson's
73% reagent

01104-143130
S S S S S S S

57

singlets at g 2.29 and 2.32 for the methyl groups and six-
proton multiplet at 2 7.02-7.31 for the thienyl protons.
The mass spectrum of 57 showed a strong molecular ion peak
at m/e 632. A long wavelength absorption of UV spectrum is
at 428 nm.

The coupling reaction of bromothiophenes by nickel and

3 could also be applied to the reaction of

reducing metals4
5-bromo-3'-4'-dimethyl-2,2'-5',2"-terthienyl 58 to give
5,51-bis-(3",4"-dimethyl-2",2"'-bithienyl)-2,2'-bithienyl 59

in modest yield (Scheme 20).

25

 

Sdmmezo
Z. ”I - W
S /s\ /S\ B. ammo”, , /s S\ IS\ IS S\ Is
58 59

The structure of 59 was confirmed by its spectral. The
1H-NMR spectrum showed two three-proton singlets at g, 2.30
and 2.33 for the methyl groups and five-proton multiplet at
6‘7.o3-7.31 for the thienyl protons. The mass spectrum of
59 showed a strong molecular ion peak at m/e 550. A long

wavelength absorption of UV spectrum is at 409 nm.

B. Synthesis of novel macrocyclic polythienyls

I. Synthesis of 12 type macrocyclic polythienyls
Retroanalysis of 12c suggests that compound 61c is a

possibly potential precursor to 12¢, since oxidation of tile

might afford the octathio[34]annulene 12c (Scheme 21) . In

Sdmnle

 

12¢ 61c

the case of porphyrins the carbon bridges have traditionally

been linked by the acid catalyzed condensation of

44,45

pyrroles. Similar strategy was applied to attempt the

26
synthesis of the- compound 61: by cyclization of 01-

quaterthienyl 14 with paraformaldehyde. First attemp was
conducted using 48% HBr as a catalyst, which resulted in the

recovery of starting material. The second attempt using the

 

SdmngZ
48%HBr
l§l§l§l§+pammmalddmyde V>61c
s s s s l-propanolA
14
P00
ounaldehde 3
14 + pmaf y 01202 611:

the Lewis acid, P0C13, as a catalyst, gave unidentifible
products.

Nevertheless, it was found later that condenstation of
a less reactive aldehyde (benzaldehyde, anisaldehyde) using
a Lewis acid (POClB, EtzAlCl, EtAlClz)- with the polythienyl
(10, 13, or 14) in methylene chloride at room temperture
allowed the successful synthesis of the symmetrical macro-
cyclic polythienyls 64 (Scheme 23). Evident supporting of

1 13

the cyclic form of 64 comes from their H and C NMR

Sdmnb23

__.. [>1
QQQ-IQI “IQI
m=0 13 R=H 64a 111:0, R=H
m=l 10 63 R=OCI-13 64b m=0,R=OCH3
”=2 1" 64c m=0, R=H

64d m=0, R=0CH3

64c m=0, R=H

64f 111:1, R=OCH3

27
spectra. Table 5 and 6 summarize the 1H and 13C spectra

data for the compound 64. The 1H-NMR spectrum of 64
generally showed a singlet at s 5.68-5.80 for the bridgehead
protons, while in the case of anisaldehyde products, a
singlet at g 3.77, 3.70, and 3.80 (methoxyl proton) was

13

observed. The C-NMR spectra displayed 9 peaks for 6411,

Table 5 ll-I-NMR Spectra of 64

 

compound bridgehead -OCH3 thienyl proton phenyl proton

 

64: 5.80 650(d. 2H) 7.38(s, 5H)
7.00(d. 2H)

64b 5.66 3.77 6.64(d, 2H) 6.82(d. 2H)
6.90(d. 2H) 7.24(d. 2H)

64c 5.70 6.71(bs, 2H) 7.35(s, 5H)
6.95(m, 41-1))

64d 5.68 3.70 6.70(bs, 2H) 6.86(d, 2H)
6.95(m, 4H) 7 .24(d. 2H)

6413 5.75 6.73(bs, 2H) 7.34(s, 5H)
6.97(m, 6H)

64! 5.71 3.80 6.75(bs, 2H) 6.87(d, 2H)

6.99(m, 6H) 7.26(d, 2H)

 

 

28

 

 

Table 6 13C-NMR spectra of 64
compound bridge C -OCI~13 thienyl phenyl
64a 47.73(d) 122.8(d), 126.8(d) 127.3(d), 128.3(d)

136.8(5), 146.5(5) 128.6(d), 142.7(5)

64b 47.00(d) 55.2(q) 122.6(d), 126.4(d) 113.9(d), 129.4(d)
136.9(5), 147.3(5) 134.8(5), 158.8(5)

64c 47.90(d) 123.0(d), 124.1(d) 127.4(d), 128.3(d)
126.9(d), 136.1(5) 128.6(d), 142.7(5)
136.6(5), 146.5(5)

64d 47.09(d) 55.2(q) 123.0(d), 123.9(d) 114.1(d), 129.3(d)
126.7(d), 136.0(5) 135.5(5), 158.7(5)
136.5(5), 146.9(5)

64o 47.90(d) 123.1(d), 124.1(d) 127.4(d), 128.3(d)
126.9(d), 135.7(5) 128.6(d), 142.7(d)
136.2(5), 136.6(5)
146.5(5)

64f 47.20(d) 55.3(q) 123.2(d), 124.1(d) 114.1(d), 129.4(d)
126.8(d), 135.7(5) 135.0(5), 159.0(5)
136.3(5), 136.5(5)
147.0(5)

 

10 peaks for 64b, 11 peaks for 64¢, 12 peaks for 6411, 12
peaks for 64c, and 13 peaks for 64!, corresponding to the
symmetrical, cyclic structure. However, the mass spectrum
(field desorption technique) showed a set of signals (i.e.
64s m/e 764, 1016, 1272, 1526; 641) m/e 568, 853, 1136, 1421,
1706) which indicated possibly a mixture of cyclic products.
correspounding to n equals, 2, 3, 4, 5....etc. Attempts to
separate the mixtures using TLC or column chromatography
failed to obtain single pure product.

Ahmed and Meth-Cohn first prepared thiaporphyrinogen
67 by the high-dilution interaction of diformyldithienyl-

' 2 9
propane 65 and the corresponding dilithio compound 66 in low

yield (Scheme 24).13 However, our attempts to cyclize di-

Sdmn224

 

formyl-a-terthienyl 35c ‘with the correspounding‘ dilithio
compound 68 (prepared by lithiation of a-terthienyl)46
resulted in the recovery of starting material (Scheme 25).
The lack of any reaction may be a result of the low solubi-

lity of 35c in THF solvent.

 

demmZS
0 ‘1’
HEW CH
8 s s
35c
4..
Wu
5 s s
68

Retroanalysis of 61b suggests the following synthetic

pathway (Scheme 26). It involes an intermolecular catalyzed

addition of dialdehydes to the activated double bond. _The

 

3O

Sdnnc26

 

61b 71

3

Michael addition of 721 to vinyl sulfone was accomplished

to give 73 in 20.8% yield (Scheme 27). However, attempts to

 

Sdmum27
()
W W-.. -
s S *1 '* e"‘\sxyr"s~ PhKMMLdMLEKNH 7’
72 20.8%
73
3

cyclize 701 with vinyl sulfone under same condition failed

to provide the desired macrocyclic molecule 71.

II. Attempts to synthesis 11 type macrocyclic polythienyls
An efficient coupling reaction for the synthesis of
linear polythienyls from simpler bromothiophenes (fide
summ, Scheme 16, 20) led us to attempt the synthesis of the
interesting macrocyclic polythienyls 11 from the correspoun-

ding bromothiophenes (Scheme 28). Table 7 summarizes the

31

Scheme 28

 

 

 

l 1
Table 7 Coupling of Various Polythienyl Dibromide
entry no. polythienyl dibromides products
1. Br W Br off white powder
5 0 s
39
s s s
42
3. Br W Br red powder
5 s s
‘74
4 Br W Br no reaction
' s s s s
75
5. Br \ \ / Br no reaction
5 s s s s
43
result of the attempted cyclization reactions. The

reactions of 39, 42, and 74 under standard conditions

yielded insoluble, unidentifiable PIOdUCtS- For example,

32
only UV spectral could be taken of the reddish product

obtained from the coupling reaction of 74 (entry 3). The
spectrum showed a long wavelength absorption at 430 nm,
which is longer than that of 5,5'-bis(3".4"-dimethyl-2"-2"'—
bithienyl)-2.2'-bithieny1 59. This is consistent with the
view that it possesses more thienyl units than 59.
Unfortunately, due to the insolubility of the product, no
other evidence (i.e. NMR, Mass spectra) could be obtained
which would prove their cyclic or linear structure as well
as the number of thienyl units.

The reaction of 75, 43 (entry 4, 5) resulted only in
the recovery of starting material due to the insoluble
nature of both compounds in the solvents tested, such as
DMAC and N,N-dimethylbenzamide. In order to overcome the
solubility problem, the use of ultrasonic irradiation was
also applied to the system. However, no product other than
starting material could be detected.

The difficulty encountered in these reactions came
mainly from the low solubility, either starting material or

products.

C. Conclusions

It has been demonstrated that various individual
unsubstituted and substituted linear polythienyls (including
both even and odd numbers of thienyl units) can be
efficiently prepared 1) by constructing a 1,4-diketone

properly substituted with thiophene groups followed by

33
treating it with Lawesson's reagent and 2) by coupling of a

simpler bromothiophene using low valent nickel. Some of the
new 3,4-disubstituted polythienyls (i.e. 55, 57, and 59)
from these reactions could be useful as candidates in the

testing of their biological properties16 or conductivi-

tyl7,18.

Finally, attempted synthesis of macrocyclic
polythienyls was severely limited by practical consideration
of solubility which decreases rapidly as the molecular

weight of the oligomers increases.

34

EXPERIMENTAL

General Methods

13

NMR spectra (1H and C) were recorded on a Bruker WM

250 MHz spectrometer using CDCl as solvent and (CH Si as

3 3’4
the internal reference. Mass spectra were obtained on a
Finnigan 4000 instrument at 70ev. Some very nonvolatile
materials were measured on JEOL HX110 HF spectrometer using
field desorption (FD) technique at Michigan State University
Mass Spectrometry Facility. High resolution mass were
measured on JEOL HXllO high resolution mass spectrometer by
Mr. Ernest Oliver. Electronic absorption spectra were
measured on a Shimatzu 160 spectrophotometer using 1 cm
matched quartz cells. Melting points were taken on a Thomas-
Hoover capillary melting point apparatus and are
uncorrected. Some high melting (>300°C) materials were
determined with an electro-thermal melting point apparatus
(Fisher Scientific) and are uncorrected. Infrared spectra
were measured on a Perkin-Elmer 599 spectrophotometer as a
Nujol mull for solids. Elemental analysis were performed by
Galbraith Laboratories, Incorporated. Dry ethyl ether,
toluene and tetrahydrofuran (THF) were obtained by distil-
lation from potassium benzophenone. Flash column chromato-

47

graphy refers to the method of Still, Kahn and Mitra using

Merck silica gel (0.040-0,063 mm).

S-Formyl-2,2’-blthlenyl (30a)

' 35
Formylation of 2,2'-bithienyl according to Uhlenbroek

5 furnished 305 in 80% yield, 111. p. 57-58°C

1

and Bijloo3
(lit35 53°C); H-NMR: g 7.00(1H, dd, J-s.o, 3.8Hz), 7.18(1H,
d, J=4Hz), 7.29(2H, m), 7.59(lH, d, J=3.8Hz), 9.8 (1H, 5):
MS: .m/e (rel. intensity) 196(M++2, 7), 195(M++1, 15),
194(M+, 84), 193(100), 165(11), 121(50): IR: cm'1 2725,

1650.

S-Formyl-2,2’-5’,2"-terthienyl (30b)

According to the general procedure of Uhlenbroek and
Bijlooas, a mixture of a-terthienyl 10 (1 g, 4 mmole), N-
methylformanilide (600 mg, 4.4 mmole) and phosphorus
oxychloride (681 mg, 4.4 mmole) was heated on steam bath for
20 min. Then the reaction mixture was decomposed by adding
an excess of an aqueous solution of sodium acetate with
stirring on steam bath for 20 min. Recrystallization of the
resulting golden yellow solid from methanol afforded 880 mg
(79.1%) of 301), m.p. 131-133°c (lit48 lac-132°C); lit-NMR: g
7.05(1H, dd, J-3.7, 4.232), 7.13(1H, d, J-3.9Hz), 7.27(4H,
m), 7.67(1H, d, J-3.9Hz), 9.86(1H, 5): MS: .m/e (rel.
intensity) 278(M++2, 14), 277(M++1, 21), 276(Mf, 100), 275

(46), 247(11), 203(23): IR: cm’1 2720, 1650.

3-Dlmethylsmino-l-(2-thienyl)-propanone (315)

According to the procedure of Wynberg34, a mixture of
2-acetylthiophene (31.5 g, 0.25 mmole), paraformaldehyde (9
g, 0.3 mmole), dimethyl aminoAHCl (24.5 g, 0.3 mmole) and

conc. HCl (1.25 ml) in 95% ethanol (30 ml) was heated under

36
reflux for 16 hrs. The resulting ppt was filtered to give

46.1 g (84.2 %) of product after cooled, m.p. 181-183°c
(lit34 179-1810C). The Mannich base hydrochloride (2.5 g)
was made alkaline (in water) using ammonia solution and
extracted with ethyl ether. The combined ethyl ether layed
was washed with saturated aqueous NaHCO3 and dried over
anhydrous MgSO4. Evaporation of the solvent gave 1.85 g of
free Mannich base which was used at once in the Michael-

Stetter reaction.

3-Dlmethylslnlno-1-(2-2’-b|thleny1)-propsnone (31b)

A mixture of 5-acetyl-2-2'-bithenyl (3 g, 14.42
mmole), paraformaldehyde (951 mg, 31.72 mmole), dimethyl
amino HCl (2.59 g, 31.72 mmole) and conc. HCl (0.1 ml) in
95% ethanol (30 ml) was heated under reflux for 16 hrs. The
resulting ppt was filtered to give 3.4 g (78.3 %) of Mannich
base hydrochloride after cooled, m.p. 221-22206.

‘ A suspension of Mannich base hydrochloride (2 g, 6.64
mmole), ethyl other (150 ml) and water (300 ml) was made
alkaline using ammonia solution which form two layers. The

ethyl ether layer was washed with sat. aqueous NaHCO and

3
dried over anhydrous MgSO4. Evaporation of the solvent and
recrystallization of the residue from 95% EtOH gave 1.62 g

(92%) of free Mannich base, m.p. 78-79OC; 1

H-NMR: 8 2.29(6H,
s), 2.77(2H, t, J=7.2Hz), 3.06(2H, t, J=7.2Hz), 7.05(1n, dd,
J=3.8, 5.0Hz), 7.17(1H, d, J=4Hz), 7.30(2H, m), 7.62(1H, d,
3:432): MS: "we (rel. intensity) 267(M++2, 2), 266(M++l, 3),

265(M+, 21), 220(74), 193(83), 179(9), 165(7), 121(48),

37
58(100).

1-(2-Th|enyI)-4-(5-2,2’-bithienyl)-l,4-butanedione (321))
A solution of 5-formyl-2-2'-bithenyl.30: (3.08 g,

15.89 mmole) in dry DMF(10 ml) under N was added dropwise

2
over a 10 min period to a suspension of KCN (516 mg, 7.93
mmole) in dry DMF (4m1). After the mixture had been stirred
for 15 min, the free Mannich base 3-dimethylamino-1-(2-
thienyl)-propanone 315 (1.1 g, 6 mole) in dry DMF (10 ml)
was addedd over a 30 min period and the resulting dark brown
solution was stirred overnight. To the crude mixture was
added 20 ml water. The tan precipitate was filtered from the
reaction mixture, thoroughly washed with ethyl ether and
recrystallization from acetone to give 3.82 g (93.5%) of
1,4-butanedione 32b, m.p. 163.5-164.s°c: Iii-NMR: 8 3.38(4H,
m),7.05(1H, dd, J85, 3.832), 7.15(1H, dd, J=3.8, 582), 7.19
(1H, d, J-4Hz), 7.32(2H, m), 7.64(1H, dd, J-l, 5Hz), 7.71

(18, d, J-4Hz), 7.82(1H, dd, J-l, 3.752): 13

c-NMR: 6 32.79,
33.27, 124.22, 125.64, 126.49, 128.13, 128.21, 132.10,
132.98, 133.65, 191.02, 191.36: MS: m/e (rel. intensity) 334
(x++2,3), 333(M++1, 4), 332(M+, 25), 221(82), 193(100), 165
(10), 121(53), 111(50): IR: cm'1 1650.

Amu. -Calcd. for C16H120283 :c, 57.80: H, 3.64

Found :C, 57.59: H, 3.82

l,4-Bis-(5-2,2’-bith1enyl)-l,4-butanedione (32c)
Method A: A solution of 5-formyl-2-2'-bithenyl 302 (1.3

g, 6.68 mmole) in dry DMF (5 ml) under N was added dropwise

2

V-

38
over a 10 min period to a suspension of KCN (208 mg, 3.19

mmole) in dry DMF (2ml). After the mixture had been stirred
-for 15 min, the free Mannich base 3-dimethy1-amino-1-(2-2'-
bithienyl)-propanone 311: (1.4 g, 5.28 mole) in dry DMF (24
ml) was addedd over a 30 min period and the resulting dark
brown solution was stirred overnight. To the crude mixture
was added water. The light yellow precipitate was filtered
from the reaction mixture, thoroughly washed with ethyl
ether and recrystallization from dioxane to give 1.9 g
(86.9%) of 1,4-butanedione 32c, m.p. 225-226°C: 1H-NMR: 5
3.37(4H, s), 7.06(IH, dd, J-3.8, 5.0Hz), 7.20(1H, d, J=4Hz),
7.30(2H, m), 7.71(1H, d, J=4Hz), MS: .m/e(rel. intensity)
416(M++2, 5), 415(x++1, 6), 414(M+, 26), 249(1), 221(100),
193(83), 179(1), 165(9), 121(40): IR: cm'1 1650.

Amfl. Calcd. for c20814°284 :C, 57.94: H, 3.40

Found :C, 57.41: H, 3.48
Method B: Divinyl sulfone (31 mg, 0.26 mole) was added

dropwise to a hot stirred solution of 5-formyl-2,2'-bithenyl
30s (100 mg,0.52 mmole), thiazolium salt (13.9 mg, 0.052
mmole) and sodium acetate (8 mg, 0.1mmole) in abs. ethanol
(2 ml). After the mixture was refluxed for 2 hrs under Ar,
the tan precipitate was filtered from the reaction mixture

and recrystallized from chloroform to give 70 mg (65%) of

32c, m.p. 225-226°C.

l-(5-2,2’-bithienyl)-4-(5-2,2’-5’,2"-terthienyl)-l,4-butenedione (32d)
A solution of 5-formyl-2,2'-5',2"-terthienyl 30b (730

mg, 2.65 mmole) in dry DMF (14 ml) under N2 was added

39
dropwise over a 15 min period to a suspension of KCN (86 mg,

1.32 mmole) in dry DMF (4m1). After the mixture had been
stirred for 15 min, the free Mannich base 3-dimethylamino-1-
(2-2'-bithienyl)-propanone 3111 (500 mg, 1.89'mmole) in dry
DMF (10 ml) was addedd over 1 hr. The resulting dark brown
solution was stirred overnight. To the crude mixture was
added water. The precipitate was filtered from the reaction
mixture, thoroughly washed with ethyl ether and
recrystallization from dioxane to give 800 mg (85.3%) of
1,4-butanedione 32d as a reddish-brown solid, m.p. 227.5-
229.5°c: MS: m/e (rel. intensity) 496(M+, 13), 330(23), 247
(12), 203(58), 193(51), 165(16), 121(73) : IR: cm“1 1650.
Amu. Calcd. for C H 0 S :C, 58.04: H, 3.25 l

24 16 2 5
Found :C, 57.83: H, 3.44

5,5’-DIformy1-2,2’-bithlenyl (35b)

According to the general procedure of Uhlenbroek and
81310035, bithienyl (2.1 g, 12.7 mmole) was added to a
mixture of N-methylformanilide (8.6 mg, 63.5 mmole) and
phosphorus oxychloride (9.75 mg, 63.5 mmole). The tempera?
ture rose gradually to 60°C. After the exothermic reaction
had ceased the mixture was warmed for 2 hrs on the steam
bath. Then the reation mixture was decomposed by adding an
excess of an aqueous solution of sodium acetate with
stirring and cooling. After standing for 1 hr at room
temperature the precipitate was filtered from the reaction

mixture, and recrystallized from CH2C12/Me0H to give 1.03

(36.5%) of 351:, m.p. 216-217°c (111:49 217-218°C): 1n-NMR: 6

40
7.42(2H, d, J-4Hz), 7.73(2H, d, J-4Hz), 9.91(2H, s): M8: m/e

(rel. inrensity) 224 (M++2, 11), 223(M++1, 21), 222(M+,
100), 221(86), 193(15), 149(52), 121(64), 108(10): IR: cm“1

2720, 1650 .

5,5’-leorn|yl-2,2’-5’,2"-terthienyl (35c)

A mixture ofci-terthienyl 10 (300 mg, 1.2 mmole), N-
methylformanilide (812 mg, 6 mmole) and phosphorus oxy-
chloride (921 mg, 6 mmole) was heated at 100°C on steam bath
for 1.5 hrs. Then the reation mixture was decomposed by
adding an excess of an excess of an aqueous solution of
sodium acetate on steam bath for 20 min with stirring. The
precipitate was filtered from the reaction mixture after
cooling, and recrystallized from benzene to give 230 mg

(63%) of 35c, m.p. 218-220°c (lit-.48 215-218°C): 1

H-NMR: 5
7.28-7.35(2H, m), 7.68(1H, d, J-4Hz), 7.69(1H, d, J-4Hz,
9.88(lH, s): MS: m/e (rel. inrensity) 306(M++2, . 12),
305(u++1, 17), 304(M+, 86), 275(7), 247(2), 43(100),

108(10): IR: cm-1

2720, 1650.
2,2’-Bis[4-(2-thienyl)-1,4-butsnedionel-thiophene (36s)

A solution of 2,5-diformylthiophene 35s (200 mg, 1.429
mmole) in dry DMF (6 ml) under N2 was added dropwise over a
10 min period to a suspension of KCN (91 mg, 1.5 mmole) in
dry DMF (6ml). After the mixture had been stirred for 15
min, the free Mannich base 3-dimethylamino-1-(2-thienyl)-
propanone 31: (437 mg, 2.38 mole) in dry DMF (6 ml) was

added over a 30 min period. The reaction mixture was stirred

' 41
overnight. To the crude mixture was added water. The tan

precipitate was filtered from the reaction mixture,
thoroughly washed with ethyl ether and recrystallization
from dioxane to give 340 mg (68%) of 1,4-butanedione 36s as

white crystals, m.p. 186-187.5°C: 1

H-NMR: 8 3.40(8H, s),
7.15 (2H, dd, J-3.8, 4.952), 7.65(1H, dd, J-l.1, 4.9Hz),
7.80(ZH, s), 7.81(2H, dd, J=1.l, 3.8Hz), MS: .m/e (rel.
intensity) 416(M+, 0.35), 277(9), 221(1), 167(5), 111(100):
IR: cm-1 1650.

Amu. Calcd. for C20H1604S3 :C, 57.67: H, 3.87

Found :C, 57.69; H, 4.13

5,5’-BIs[4-(2-thienyl)-l,4-butsnedionel-2,2’-bithienyl (36b)

A solution of 5,5'-diformyl-2,2'-bithienyl 35b (444
mg, 2 mmole) in dry DMF (60 ml) under Ar was added dropwise
over a 10 min period to a suspension of KCN (130 mg, 2
mmole) in dry DMF (2ml). After the mixture had been stirred
for 15 min, the free Mannich base 3-dimethylamino-1-(2-
thienyl)-propanone 312 (581 mg, 3.17 mole) in dry DMF (5
ml) was addedd over a 30 min period and the reaction mixture
was stirred overnight. To the crude mixture was added water.
The yellow-orange precipitate was filtered from the reaction
mixture, thoroughly washed with ethyl ether and recrystal-
lized from dioxane to give 540 mg (68.4%) of 1,4-butanedione
36b, m.p. 255.5-256.5°C: 1H-NMR: 5 3.38(4H, t, J-4.8Hz),
3.40 (4H, t, J=4.8Hz), 7.19-7.82(10H, m): MS: .m/c'(rsl.
intensity) 498(M+, 4), 387(14), 359(10), 220(9), 111(100):

high resolution mass calcd. for C24H1804S4 498.0084: found

_1 42
498.0078: IR: cm 1650.

Anal. Calcd. for C24I'11804S4 :C, 57.81; H, 3.64

Found :c, 57.85: H, 4.6050
5-Bromo-5’-formyl-2,2’-bithenyl (38)

A mixture of 5-formy1-2,2'-bithenyl (1 g, 5.15 mmole),
and pyridine hydrobromide (1.65 g, 5.15 mmole) in CHCl3 (100
ml) was stirred for 2 hrs at room temperature. The reaction
mixture was washed with sat. NaHCO3 solution, dried over
anhydrous Mgso4 and concentrated in wuuo. Recrystal-
lization the residue from petrolium ether (50°C-110°C) gave
1.10 g (78.5%) of 38 as a greenish solid, m.p. 144.5-

145.5°c: 1

n-NMR: 8 6.98(1H, d, J-3.8Hz), 7.05(1H, d,
J-3.8nz), 7.12(1H, d, J-3.8Hz), 7.60(lH, d, J-3.8Hz): ms:
nu? (rel. intensity) 274(M++2, 98), 272(M+, 100), 245(8),

243(7), 199(18), 197(1), 121(34): IR: cm-1

1655 .
l,4—Bls-(2-bromo-5-thlenyl)-1,4-butsnedlone (39)

Divinyl sulfone (295 mg, 2.5 mmole) was added dropwise
to a hot stirred solution of 2-bromo-5-formylthiophene (955
mg, 5 mmole), thiazolium salt (134.9 mg, 270 mmole) and
sodium acetate (82 mg, 1 mmole) in abs. ethanol (5 ml).
After' the mixture was refluxed for 4 hrs under Ar, it was
poured into water, and the resulting mixture was extracted
with CHC13. The organic layer was washed with water several
times, dried over anhydrous M9804 and concentrated.
Recrystallization the residue from abs. EtOH gave 195 mg

1

(19.2%) of 39 as a light yellow solid, m.p. 175-176°C: H-

43
NMR: 2. 3.20(2H, s), 7.o4(1H, d, J=4Hz), 7.46(1H, d, J=4Hz):

13c-NMR: 2. 32.42, 122.86, 131.30, 132.25, 145.05, 190.14:
us: "we (r61. intensity) 410(M++4, 6), 408(M++2, 16),
406(M+, 6), 217(16), 190(32), 189(100), 161(11), 117(16),

82(63): IR: cm"1 1650.

l,4-Bls-(5-bromo-S’-2,2’-blthlenyl)-1,4-butanedlone (40)

Divinyl sulfone (88.6 mg, 0.75 mmole) was added
dropwise to a hot stirred solution of 5-bromo-5'-formyl-
2,2'-bithenyl 38 (408 mg, 1.5 mmole), thiazolium salt (41
mg, 0.15 mmole) and sodium acetate (25 mg, 0.31 mmole) in
abs. ethanol (20 ml). After the mixture was refluxed for
4.5 hrs under Ar, the yellow precipitate was filtered from
the reaction mixture to give 190 mg (44.4%) of 40, m.p.

225°C (dec.): 1

H-NMR: é: 3.28(2H, s), 7.55(1H, d, J-4Hz),
7.66(lH, a, J-4Hz) 7.85(1H, d, J-4Rz), 7.92(1H, d, J-4Hz):
us: aye (rel. intensity) 574(M++4, 13), 572(M*+2, 15),
570(M+, 7), 301(92), 299(100), 273(82), 271(79), 245(11),

243(11), 201(35), 199(27): IR: cm'1 1649.

l,4-BIs-(S-formyl-5‘-2,2’-blthienyl)-1,4-butanedlone (41)

Divinyl sulfone (88.5 mg, 0.75 mmole) was added
dropwise to a hot stirred solution of 5,5'-diformyl-2,2'-
bithenyl.35b (333 mg, 1.5 mmole), thiazolium salt (40 mg,
0.15 mmole) and sodium acetate (25 mg, 0.31mmole) in abs.
ethanol (80 ml). After the mixture was refluxed for 17 hrs
under Ar, the orange precipitate was filtered from the

reaction mixture to give 150 mg (43%) of 41, m.p.

44
255°C(dec.): 1H-NMR: 8 3.34(2H, s), 7.32(1H, d, J=4Hz),

7.33(lfi, d, J=4Hz) 7.65(1H, d, J=4Hz), 7.70(1H, d, J=4Hz),
9.85(1H, 8); MS: m/e (rel. intensity) 470(M+, 3), 442(3),
414(trace), 221(100), 149(36), 121(20): IR: cm"1 2720, 1655,

1625.

a-Quaterthlenyl (14)

A mixture of the 1,4-butanedione 320 (3 g, 9.36 mole)
and Lawesson's reagent (2.19 g, 5.42 mmole) in dry toluene
(180 ml) was refluxed under Ar for 1 hr. The yellow-orange
precipitate was filtered from the reaction mixture and
recrystallized from 95% ethanol to give 2.77 g (93%) of 14,
m.p. 212-213°c (lit30 211-212°C): us: m/e (rel. intensity)

334(x++2, 1), 333(M++l, 3), 332(M+, 100), 165(8).

a-Qulnquethlcnyl (15)

Method A: A mixture of the 1,4-butanedione 32c (500 mg,
1.2 mmole) and Lawesson's reagent (293 g, 0.73 mmole) in dry
toluene (100 ml) was refluxed under Ar for 4.5 hrs. The red
precipitate was filtered from the reaction mixture and
thoroughly washed with ethanol to give 468 mg (94%) of 15,
m.p. 256-257°c (11t3° 256-258°C): MS: m/e (rel. intensity)
414(M++2, 18), 413(M++1, 18), 412(M+, 82).

Method B: A mixture of the bis(1,4-butanedione) 362 (100
mg, 0.24 mmole) and Lawesson's reagent (116 g, 0.288 mmole)
in dry toluene (20 ml) was refluxed under Ar for 1 hr. 'The
precipitate was filtered from the reaction mixture and

thoroughly washed with ethanol to give 90 mg (91%) of'ls,

A -—v..-.v-

o 45
m.p. 256.5-257.5 c.

a-Sexlthlenyl (16)

Method A: A mixture of the 1,4-butanedione 32d (200 mg,
0.4 mmole) and Lawesson's reagent (97 g, 0.24 mmole) in dry
toluene (200 ml) was refluxed under Ar for 24 hrs. The
orange precipitate was filtered from the reaction mixture
and thoroughly washed with ethanol to give 169 mg (85.5%)
of 16, m.p. 302-303°c (111:28 304-305°C): us: m/e (rel.
intensity) 496(M++2, 28), 495(M++1, 28), 494(M+, 100),
247(63).

Method B A mixture of the bis(1,4-butanedione) 361) (227
mg, 0.46 mmole) and Lawesson's reagent (221 g, 0.56 mmole)
in dry toluene (200 ml) was refluxed under Ar for overnight.
The orange precipitate was filtered from the reaction
mixture and thoroughly washed with ethanol to give 207 mg

(91%) of 16, m.p. 307-308°c.

S,S"-ler0mo-2,2’,5’,2"-terthIenyl (42)

A mixture of the 1,4-butanedione 39 (100 mg, 0.246
mmole) and Lawesson's reagent (60 mg, 0.148 mmole) in dry
toluene (20 ml) was refluxed under Ar for 20 min. The
reaction mixture was subjected to flash column
chromatography (slica gel, CHZClz/petrolem ether (35-60°C)
1:1) to furnish a greenish-yellow solid. Recrystallization
of the crude product from abs. EtOH gave 70 mg (70.4%) of
42, m.p. 160-161°c (lit51 160-161°C): MS: "we (rel.

intensity) 408(M++4, 46), 406(M++2, 100), 404(Mf, 46),

46
325(5) 283(17), 281(17), 246(4).

1,12-mbromo-aL-quinquethienyl (43)

A mixture of the 1,4-butanedione 40 (100 mg, 0.175
mmole) and Lawesson's reagent (43 mg, 0.05 mmole) in dry
toluene (100 ml) was refluxed under Ar overnight. The
orange precipitate was filtered from the reaction mixture
to give 53 mg (53.3%) of'43, m.p. 289-291°C . This compound
is too insoluble to obtain NMR spectra: MS: .m/e (rel.
intensity) 572(M++4, 70), 570(M++2, 100), 568(M+, 38),
492(6), 490(6), 489(2), 447(18), 445(14), 285(16): high
resolution mass cacld. for C H s Br 567.7763: found

20 10 5 2
567.7749.

S-Bromo-2,2’-5’,2”-terthlenyl (45)

A mixture ofoL-terthienyl (500 mg, 2 mmole), and
pyridinium perbromide (644 mg, 2 mmole) in CHCl3 (100 ml)
was stirred for 2 hrs at 0°C. The reaction mixture was
washed with sat. NaI-ICO3 solution, dried over anhydrous Hgso4
and concentrated in wuuo. Recrystallization of the residue
from abs. EtOH gave 400 mg (61.3%) of 45 as a greenish

solid, m.p. 133-134.5°C; 1

H-NMR: 6 6.8-7.2(m) ; MS: .m/e
(rel. intensity) 328(M++2, 57), 326(M+, 62), 247(20),

203(68).

Coupling of 44 to 5,5’-diformyl-2,2’-bithienyl (35b)
A 50-ml round-bottomed, two-necked flask was charged

with NiCl2 (130 mg, 1 mmole), triphenylphosphine (2 g, 7.6

47
mmole), and Zn dust (1 g, 15 mmole). A rubber serum cap was

placed over one neck of the flask and a stopcock adapter in
the other. The flask was evacuated and flushed with Ar
several times. Dry DMAC (N,N-dimethylacetamide) (10 ml) was
added via syringe through the serum cap. The reaction flask
was then placed in an oil bath at 80°C and stirred
magnetically. After the red-brown catalyst had formed, a
Ar-purged solution of 5-bromo-2-thiophene-carboxaldehyde 44
(1.9 g, 10 mmole) in DMAC (2 ml) was added via syringe to
the reaction mixture. The reaction was conducted at 80°C
for overnight. The precipitate was filtered and washed with
water. The solid was dissolved in methylene chloride and
the solution was filtered to remove Zn. Evaporation of the
solvent gave 586 mg (52.8%) of 35b, m.p. 214-215°C (lit‘l'9

217-218°C).

Coupling of 38 to l,l0’-dlformyl-a-quaterthlenyl (47)

A 25-ml round-bottomed, three-necked flask was charged
with NiCl2 (6 mg, 0.046 mmole), triphenylphosphine (74 mg,
0.281 mmole), and Zn dust (76 mg, 1.163 mmole). A rubber
serum cap was placed over middle neck of the flask, stopcock
adapter in the other and one bent tube charged with.38 (50
mg, 0.184 mmole) was placed over another neck. The flask was
evacuated and flushed with Ar several times. Dry DMAC (1
ml) was added via syringe through the serum cap. The.
reaction flask was then placed in an oil bath at 80°C 'and
stirred magnetically. After the red-brown catalyst had

formed, the 38 in the bent tube was poured into the rection

48
mixture and maintained at 80°C for overnight. The

precipitate was filtered and washed with CHC13. The solid
was then tri-turated with 10% HCl to remove Zn, followed by
washing with water and dried to give 18mg (50.7%) of 47 as a
orange solid, m.p. 200°C (dec): MS: .m/e (rel. intensity)

386(M+, 34), 358 (3), 193(9), 183(15), 44(100).

Coupling of 45 to -sexlth1euyl (16)

A 25-ml round-bottomed, three-necked flask was charged
with NiCl2 (4 mg, 0.03 mmole), triphenylphosphine (59 g,
0.225 mmole), and Zn dust (29 mg, 0.45 mmole). A rubber
serum cap was placed over middle neck of the flask, stopcock
adepter in the other and one bent tube charged with 45 (97.8
mg, 0.3 mmole) was placed over another neck. The flask was
evacuated and filled with Ar several times. Dry DMAC (1 ml)
was added via syringe through the serum cap. The reaction
flask was then placed in an oil bath at 80°C and stirred
magnetically. After the red-brown catalyst had formed, the
45 in the bent tube was poured into the rection mixture The
reaction was conducted at 80°C for overnight. The
precipitate was collected from the reation mixture, washed.
with CHCl3. The precipitate was triturated with 10% HCl to
remove Zn and filtered. The solid was washed with water and

dried to give 40 mg (54%) of 16 as a red solid, m.p. 302-

304°c ( 11t28 304-305°C).

l,4-Bls-(2-thlenyl)-2,3-dImethyl-1,4-butanedl0ne (49)

n-Butyllithium (0.12 mOle, 2.5 M in hexane) was added

49
dropwise to a stirred solution of diisopropylamine (12.12 g,

0.12 mole) in dry THF (30 ml) at -78°c under Ar. After 15
min, 2-propionylthiophene (15.12 g, 0.108 mole) was added
dropwise at the same temperature. The mixture was stirred
for 30 min, and anhydrous CuCl2 (16.128 g, 0.12 mole) in dry
DMF (60 ml) was added in one portion. The dark solution
stirred for an additional 10 min at -78°C and warmed up to
room temp. and stirred overnight. After addition of 150 ml

of 3% HCl, the mixture was extracted with CH Cl2 three

2
times. The combined organic layer was washed sucessively
with 3% HCl, water, dried over anhydrous M'gso4 and
concentrated. The residue was flash column chromatographed
over silica gel, using ethyl acetate-hexane (1:4) as eluent,
after recrystallization from abs. EtOH to give 1.85 9

1H-NMR: 8

(12.3%) of one diastereomer of 49, m.p. 94-95.5°C:
1.33(3H, d, J-6.9Hz), 3.75(1H, m), 7.12(1H, dd, J-3.8,
5.032), 7.60 (13, dd, J=1.1, 5.0Hz), 7,79(1H, dd, J-1.l,
3.8Hz): MB: nu? (rel. intensity) 278(M+, 6): high resolution
mass calcd. for C14H14°252 278.0432: found 278.0429: IR: cm-
1 1650. further elution furnished 0.92 g (6.1%) of another

1H-NMR: 8 1.18(3H, d,

diasteromer of 49, m.p. 123-125°C:
J-6.3Hz), 3.77(lH, m), 7.16(1H, dd, J-3.8, 5.0Hz), 7.69(lH,

dd, 331.1, 5.0HZ), 7,84 (1H, dd, J=1.1, 3.8Hz).

3’,4’-Dimethyl-2,2’-5’,2"-terthienyl (50)
A mixture of the 1,4-butanedione 49 (300 mg, 1.079
mmole) and Lawesson's reagent (262 mg, 0.65 mmole) in dry

toluene (2 ml) was refluxed under Ar for 15 min. The

50
reaction mixture was subjected to flash column chromato-

graphy (slica gel, CHZClz/petrolem ether (BS-60°C) 1:1). to
furnish a tan solid. Recrystallization of the crude product
from Neon gave 228 mg (76.6%) of'so as a white solid m.p.

1

126-128°c (111:38 128°C): H-NMR: 6 2.3(3H, s), 7.07(1H, dd,

J=3.6, 5.0HZ), 7.13(1H, dd, J=3.6, 1.0HZ), 7.31(1H, dd,

J-1.0, 5.0Hz); 13

C-NMR: 8 14.30, 125.30, 125.94, 127.42,
129.50, 135.15, 136.35: us: m/e (rel. intensity) 278(M++2,

16), 277(M++1, 20), 276(M+, 100).

5-Formyl-3’,4’-dimethyl-2,2’-5’,2"-terthienyl (53)

A mixture of a-terthienyl so (552 mg, 2 mmole), N-
methylformanilide (298 mg, 2.2 mmole) and phosphorus
oxychloride (338 mg, 2.2 mmole) was heated on steam bath for
10 min. Then the reaction mixture was decomposed by adding
an excess of an aqueous solution of sodium acetate with
stirring on steam bath for 20 min. The mixture was extracted
with CHZC12.
anhydrous Mgso4 and concentrated in wwuo. The residue was

The combined organic fractions were dried over

flash column chromatographed (silica del, CHCl3) to give 170
mg (30.8%) of so, 320 mg (52.6%) of the title compound.53,.

m.p. 115-116.5°c (95% Eton): 1

H-NMR:.5 2.29(3H, s), 2.35(3H,
s), 7.07(1H, dd, J=3.7, 5.0Hz), 7.15(1H, dd, J-1.1, 3.6Hz),
7.21(1H, d. J=4.0Hz), 7.32(1H, dd, J=1.l, 5.0Hz), 7.68(1H,
d, J=4.0Hz), 9.85(1H, 3): MS: m/e (rel. intensity) 306(M++2,
10), 305(M++l, 15), 304(M+, 100): IR: cm"1 2725, 1650.
Further elution furnished 28 mg (4.2%) of 5,5'-formyl-3',4'-

dimethyl-2,2'-5',2"-terthienyl m.p. 199-201°c (95% EtOH):

51
1H-NMR: 8 2.32(3H, s), 7.20(1H, d. J=4.0Hz), 7.67 (1H, d,
J24.OHz), 9.83(1H, s): MS: m/e (rel. intensity) 334 (M++2,

12), 333(u++1, 19), 332(M+, 100).

1-(2-Thlenyl)-4-(3’,4’-dlmethyl-2,2’-5’,2"-terthlenyl)-l,4-butanedione (S4)

A solution of 5-formyl-3',4'-dimethyl-2,2'-5',2"-
terthienyl 53 (400 mg, 1.316 mmole) in dry DMF (7 ml) under
Ar was added dropwise over a 10 min period to a suspension
of KCN (43 mg, 0.66 mmole) in dry DMF (1.5ml). After the
mixture had been stirred for 15 min, the free Mannich base
3-dimethylamino-1-(2-thienyl) -propanone 312 (50 mg, 0. 274
mmole) in dry DMF (5 ml) was addedd over a 30 min period and
the reaction mixture was stirred overnight. To the crude
mixture was added water. The orange precipitate was filtered
from the reaction mixture, thoroughly washed with ethyl
ether and recrystallized from dioxane/H20 to give 340 mg
(58.5%) of 1,4-butanedione:54, m.p. 156-158°c: 1n-NMR: g
2.25(s, 3H), 2.30(s, 3H),3.33(4H, t, J=4.8Hz), 7.02(1H, dd,
383.8, 5.0HZ), 7.09(2H, m), 7.27(lH, d, J=4.8Hz), 7.58( 13,
d, J-4.8Hz), 7.70(1H, d, J-4Hz), 7.76(1H, d, J-4Hz): us: m/e
(rel. intensity) 442(M+, 64): high resolution mass calcd.
for 0223180284 442.0186: found 442.0200: IR: cn'1 1650.
3’,4’-Dlmethyl-a-quinquethienyl (55)

A mixture of 1,4-butanedione 55 (300 mg, 0.68 mmole)
and Lawesson's reagent (165 mg, 0.408 mmole) in dry toluene

(5 ml) was refluxed under Ar for 20 min. The reaction

mixture was subjected to flash column chromatography (slica

52
gel, CHZClZ/petrolem ether (35-60°C) 1:1) to furnish a

solid. Recrystallization of the crude product from
dioxane/H20 gave 250 mg (83.6%) of 55 as a orange-yellow

solid, m.p. 135-136.5°C: 1

H-NMR: 8 2.23(BH, s), 6.92-
7.24(1on, m): us: m/e (rel. intensity) 442(M++2, 17),
441(M++1, 20), 440(M+, 100): high resolution mass calcd.
for C22H16°5 439.9853: found 439.9818.
1,4-BIs-(3’,4’-dlmethyl-2,2’-5’,2"-terthlenyl)-l,4-butenedlone (56)

Divinyl sulfone (78 mg, 0.658 mmole) was added
dropwise to a hot stirred solution of 5'-formyl-3',4'-
dimethyl-2,2'-5',2"-terthieny1 53 (400 mg, 1.315 mmole),
thiazolium salt (35 mg, 0.132 mmole) and sodium acetate (22
mg, 0.263mmole) in abs. ethanol (20 ml). After the mixture
was refluxed under Ar for overnight, the orange-yellow
precipitate was filtered from the reaction mixture and
recrystallized from dioxane/H20 to give 250 mg (60%) of 56,
m.p. 205-206°c: 1H-NMR: 8 2.25(3H,s), 2.31(3H, s), 3.33(2H,
s), 7.02(1H, dd, J=3.7, 5.0Hz), 7.10(2H, m), 7.27(1H, dd, J8
1.0, 5.0Hz), 7.70(1H, d, J-4Hz); MS: m/e (rel. intensity)
635(M++l, 8), 634(M+, 13), 331(100), 167(21), 113(13), 55
(172): high resolution mass calcd. for C H S 0 634.0246:

32 26 6 2
found 634.0225: IR: cm'1 1650.

2,5-Bi:-(3",4"-dlmethyl-2’,2"-5",2’”-terthleuyl)-t'hiopheue (57)
(A mixture of 1,4-butanedione 56 (30 mg, 0.047 mmole)
and Lawesson's reagent (12 mg, 0.028 mmole) in dry toluene

(2 ml) was refluxed under Ar for 2 hrs. The precipitate was

53
collected to give 15 mg (50.5%) of 55 as a orange solid, m.p.

205-207°c: 1

H-NMR: 8 2.29(3H, s), 2.32(3H, 8), 7.02-7.31(6H,
m): MS:.m/e (rel. intensity) 634(M++2, 22), 633(M++1, 37),
632(M+, 87): high resolution mass calcd. for C32H24S7

631.9912: found 631.9953.

S-Btomo-3’,4’-dimethyl-2,2’-5’-2"-terthienyl (58) and 5,5-dibromo-3’,4’-dimethyl-
2,2’-5’-2"-terthienyl (74)

A mixture of 3',4'-dimethyl-2,2'-5',2"-terthienyl 50
(500 mg, 1.81 mmole) and N-bomosuccinimide (332 mg, 1.81
mmole) in CCl4 (50 ml) was stirred for 3 hrs at 0°C. The
succinimide formed was removed by filtration. After removal
of solvent, the residue was flash column chromat-graphed
using hexanes as eluent to give 437 mg (68.2%) of title
compound 58 (Rf=0.86) as a pale yellow solid, m.p. 79-81°C:
1H-NMR: 8 2.25(3H, s), 2.28(3H, s), 6.85(1H, d, J=3.9 Hz),
7.00(1H, d, J-3.9Hz) , 7.05(li-i, dd, J-3.6, 5.1 HZ) , 7.12 (18,
dd, J-3.6, 1.232), 7.30(1H, dd, J-1.2, 5.132): MS:.m/e (rel.
intensity) 356(M++2, 58), 354(M+, 100). Further elution
furnished 100 mg (12.8%) of 5,5—dibromo-3',4'-dimethy1-2,2'-‘

5',2"-terthienyl 74 , m.p. 128-129°C(abs. EtOH), 1

H-NMR: 5
2.19(3H, s), 6.79(1H, d, J-3.8Hz), 6.95(1H, d, J- 3.8Hz):

us: m/e (rel. intensity) 432(M++, 17).

Coupling of 58 to 5,5’-bis(3",4"-dimethyl-2",2"‘-bithenyl)-2,2’-bithienyl (59)
A 25-ml round-bottomed, three-necked flask was charged
with NiCl2 (7 mg, 0.056 mmole), triphenylphosphine (110 g,

0.423 mmole), and Zn dust (110 mg, 1.692 mmole). A rubber

54
serum cap was placed over middle neck of the flask, stopcock

adapter in the other and one bent tube charged with 58 (95
mg, 0.208 mmole) was placed over another neck. The flask was
evacuated and flushed with Ar several times. Dry DMAC (1 ml)
was added via syringe through the serum cap. The reaction
flask was then placed in an oil bath at 80°C and stirred
magnetically. After the red-brown catalyst had formed, the
58 in the bent tube was poured into the rection mixture and
maintained at 80°C for overnight. The precipitate was
filtered and washed with CHC13. The solid was then
triturated with 10% HCl to remove Zn followed by washing
with water and dried to give 30mg (40.7%) of 59 as a egg

1H-NMR: 6 2.30(3H, s),

yellow solid, m.p. 245-247°C:
2.33(3H, s), 7.03-7.31(5H, m): MS: m/e (rel. intensity)
552(n++2, 172), 551(M++l, 41), 550(M+, 100), 275(13): high
resolution mass calcd. for °28H22°6 550.0042: found

550.0017.

Cyclization of 13 with 62 (64a)

Phosphorus oxychloride (277 mg, 1.80 mmole) was added
to a solution of bithenyl 13 (150 mg, 0.9 mmole) and
benzaldehyde 62 (1.9g, 18 mmole) in CH2C12 (80 ml) at 25°C
and stirred for 42 hrs. Evaporation of the solvent to one-
third and flash column chromatography of the reaction

mixture using CHCl as eluent gave 176 mg of 64s as a deep-

1

3
green solid, m.p. 80°C (dec.); H-NMR: 8 5.8(1H, m), 6.5(2H,

m), 7.0(2H, m), 7.38(5H, sb): 13c-NMR: 8 47.73(d), 122.8(d),

126.8(d), 127.3(d), 128.3(d), 128.5(d), 136.8(8), 142.7(8),

55
146.5(9): MS(FD)°2: m/e (rel. intensity) 1526(8), 1525(10),

1272(28), 1182(75), 1016(45), 928(100), 764(7).

Cyclization of 13 with 63 (64b)
Phosphorus oxychloride (1 g, 6.6 mmole) was added to a
solution of bithienyl 13 (500 mg, 3.0 mmole) and

anisaldehyde 63 (8.16g, 60 mmole) in CH C12 (150 ml) at 25°C

2
and stirred for 28 hrs. Evaporation of the solvent to one-
third and flash column chromatography of the reaction
mixture using CHCl3 as eluent gave 145 mg of 640 as a green
solid, m.p. 124°C (dec.): 1H-NMR: 8 3.77(3H, 9), 5.661H, m),

6.64(2H, m), 6.84(2H, d), 6.90(2H, m), 7.24(2H, d); 13

C-NMR:
8 47.0(d), 55.2(g), 113.9(d), 122.6(d), 126.4(d), 129.4(d),
134.8(9), 136.9(9), 147.3(9), 158.8.5(9): MS(FD)°2: .m/e
(rel. intensity) 1706(86), 1421(21), 1136(55), 853(48),

710(100), 568(90), 372(85) .

Cyclization of 10 with 62 (64c)
Phosphorus oxychloride (123 mg, 0.8 mmole) was added\
to a solution ofcfi-terthenyl 10 (100 mg, 0.4 mmole) and

benzaldehyde 62 (848 mg, 8 mmole) in CH CI2 (40 ml) at 25°C

2
and stirred for 24 hrs. Evaporation of the solvent to half

and -f1ash column chromatography of the reaction mixture

using CHCl3 as eluent gave 135 mg of 644: as a yellow-

1

greenish solid, m.p. 140°C (dec.); H-NMR: b 5.70(1H, bs),

6.71(ZH, bs), 6.95(4H, m), 7.35(5H, Sb); 13

C-NMR: 8 47.9(d),
123.0(d), 124.1(d), 126.9(d), 127.4(d), 128.3(d), 128.6(d),

136.1(9), 136.6(9), 142.7(9), 146.5(9): MS(FD)52: "we (rel.

56
intensity) 1009(100) , 672 (15) .

Cyclization of 13 with 63 (640)

Phosphorus oxychloride (123 mg, 0.8 mmole) was added
to a solution ofLX-terthienyl 10 (100 mg, 0.4 mmole) and
anisaldehyde 63 (1g, 8 mmole) in CHZC12 (40 ml) at 25°C and
stirred for 68 hrs. Evaporation of the solvent to half and
flash column chromatography of the reaction mixture using
CI-ICl3 as eluent gave 60 mg of 64d as a yellowlish-green

1

solid, m.p. 115°C (dec.): H-NMR: 8 3.7(3H, 9), 5.68(1H,

bs), 6.70(2H, bs), 6.86(2H, d), 6.95(4H, m), 7.24(2a, d):
13C-NMR: 2: 47.09(d), 55.2(q), 114.1(d), 123.0(d), 123.9(d),
126.7(d), 129.3(d), 135.5(9), 136.0(9), 136.5(9), 146.9(9),
158.7(9): MS(FD)52: m/e (rel. intensity) 1099(18), 979

(100) , 732(5).

Cyclization of 14 with 62 (64c)

Phosphorus oxychloride (808 mg, 5.26 mmole) was added
to a solution oftX-quaterthienyl 14 (810 mg, 2.45 mmole) and
benzaldehyde 62 (5 ml) in CH2C12 (400 ml) at 25°C and
refluxed for 48 hrs. Evaporation of the solvent to half and
double flash column chromatography of the reaction mixture
using CHCl3 as eluent gave 405 mg of 64e as a greenish-
yellow solid, m.p. 145°C (dec.): 1H-NMR: é) 5.75(1H, bs),

6.73(ZH, bs), 6.97(6H, m), 7.34(sn, 9b): 13

C-NMR: 8 47.9(d),
123.1(d), 124.1(d), 126.9(d), 127.4(d), 128.3(d), 128.6(d),
135.7(9), 136.2(9), 136.6(9), 142.7(9), 146.5(9): MS(FD)°2:

nu? (rel. intensity) 1675(38), 1586(80), 1420(55), 1256(87),

57
1186(100), 838(70), 418(45).

Cyclization of 14 with 63 (641')

Phosphorus oxychloride (205 mg, 1.33 mmole) was added
to a solution ofcx-guaterthenyl 14 (200 mg, 0.6 mmole) and
anisaldehyde 63 (1.638g, 12 mmole) in CH2C12 (180 m1) at
25°C and refluxed for 7 days. Evaporation of the solvent to
half and double flash column chromatography of the reaction
mixture using CHC13 as eluent gave 90 mg of 64! as a

1

greenish-yellow solid, m.p. 140°C (dec.): H-NMR: 6 3.80(3H,

9), 5.71(13, bs), 6.76(23, bs), 6.99(63, m), 6.87(23, d),

7.26(23, d): 13

C-NMR: 5 47.2(d), 55.3(g), 114.1(d),
123.2(d), 124.1(d), 126.8(d), 129.4(d), 135.0(9), 135.7(9),
136.3(9), 136.5(9), 147.0(9), 159.0(9): MS(FD)52:.m/e (:91.
intensity) 1796(20), 1677(39), 1346(100), 1226(85), 898(25),

449 (30) .

l,4-Bis(2,2-dithienylmethane)-1,4-diketone (73)

Divinyl sulfone (90 mg, 0.758 mmole) was added
dropwise to a hot stirred solution of 5-formy1-2,2'-
dithienylmethane 72 (316 mg, 1.52 mmole), thiazolium salt
(41 mg, 0.152 mmole) and sodium acetate (24 mg, 0.304mmole)
in abs. ethanol (15 ml). After the mixture was refluxed
under Ar for overnight, the precipitate was filtered from
the reaction mixture and recrystallized from dioxane/320 to
give 250 mg (60%) of 73, m.p. 160°C(dec.): 13-NMR: 8
3.28(23, 9), 4.34(23, s), 6.87-6.94(33, m), 7.17(13, dd,

J-0.9, 5.032), 7.62(1H, d, J-3.832): MS: m/e (rel.

58
intensity) 442(M+, 5), 263(37), 207(100), 135(14), 79(27):

IR: cn'1 1650.

1,10-Dibromo-oL-quaterthienyl (75)

A suspension ofck-quaterthienyl (100 mg, 0.303 mmole),
and pyridinium perbromide (194 mg, 0.606 mmole) in CHCl3 (30
ml) was refluxed for 3 hrs. The precipitate was filtered
from the reaction mixture and recrystallized from toluene to
give 400 mg (61.3%) of 75 as a golden yellow solid, m.p.
261-263°C (lit20 251°C): MS: m/e (rel. intensity) 490(3++4,
52), 488(M++2, 100), 486(M+, 39), 410(3), 409(3), 408(3),

407(2), 365(23) , 363(22) .

APPENDIX

59

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BIBLIOGRAPHY

'77

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50. The NMR spectra indicate an impurity of dioxane. Amfl.
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52. Mass spectra were recorded by Jon HX110 HF mass spectro-

meter using field desorption (FD) technique from the
Michigan State Univ. Mass Spectrometer Facility.