Studies in the Dithienylbenzo[c]thiophene Series

Article abstract of DOI:10.1021/jo980246a

A number of derivatives of 1,3-dithienylbenzo[c]thiophene have been synthesized. The mono- and dicarboxaldehydes have been elaborated to give new vinylenes and cyanovinylenes. β-Dodecyl-and hexyl-substituted analogues have been prepared. Results from cyclic voltammetric investigation as well as fluorescence studies are reported.

Full text of DOI:10.1021/jo980246a

J . Org. Chem. 1998, 63, 3105-3112
3105
Stu d ies in th e Dith ien ylben zo[c]th iop h en e Ser ies
A. K. Mohanakrishnan, M. V. Lakshmikantham, Carol McDougal,† Michael P. Cava,*
J effrey W. Baldwin, and Robert M. Metzger
Department of Chemistry, The University of Alabama, Box 870336, Tuscaloose, Alabama 35487-0336
Received February 10, 1998
A number of derivatives of 1,3-dithienylbenzo[c]thiophene have been synthesized. The mono- and
dicarboxaldehydes have been elaborated to give new vinylenes and cyanovinylenes. â-Dodecyl-
and hexyl-substituted analogues have been prepared. Results from cyclic voltammetric investigation
as well as fluorescence studies are reported.
Sch em e 1
In tr od u ction
In recent years, there has been tremendous interest
in organic molecules that can be further elaborated into
materials exhibiting promising electrochemical, optical,
and electronic effects that are desirable in the fabrication
of electroluminiscent devices, frequency doublers, radio
frequency/electromagnetic interference shielding devices,
etc.1-5 In this regard, thiophene derivatives have played
a very significant role. For example, polythiophene is
superior to polyphenylene as a semiconductor; poly(thie-
nylenevinylene) has attracted considerable interest as a
material with enhanced third-order nonlinear suscepti-
bilities. The arylenevinylenes and other heteroaryl-
enevinylenes have also attracted attention in the fabrica-
tion of electroluminiscent devices.6
Since 1992, the synthesis of 1,3-dithienylbenzo[c]-
thiophene (1) and its electrochemical behavior have been
reported independently by four groups.7a-d Electropoly-
merization of 1 led to the formation of a material with
poor conductivity. The polymer from 1 was also deposited
on ITO glass. A detailed optoelectronic study of this
polymer provided a value of ∼1.7 eV for its band gapsa
value intermediate between that of poly(isothianaph-
thene) (∼1.0 eV) and polythiophene (2.0 eV). No further
chemical transformations of the ring system of 1 were
reported. Since it has been well established that anel-
lation of aromatic rings to thiophene, as, for example, in
benzo[c]thiophene, greatly changes the properties of
materials derived from such a substrate, synthetic work
was undertaken to modify 1,3-dithienylbenzo[c]thiophene,
so as to provide routes to new extended oligomers,
vinylenes, etc. This also provided an opportunity to
study, albeit qualitatively, the spectroscopic and electro-
chemical behavior of some of these extended systems.
We now report recent results from our laboratories on
the transformations of 1,3-dithienylbenzo[c]thiophene (1),
as well as the synthesis of the dodecyl derivative 2, the
hexyl derivative 3, and the bromo derivative 4 and their
transformations. Additional oligomers 7 and 8 were
prepared.
Resu lts
The first targets were the substituted derivatives 2 and
3, which were best made by the action of the appropriate
thienyl Grignard reagent on the known lactone 5 followed
by thionation of the intermediate 6 (Scheme 1).
The bromo derivative 4, 1,3-dibithienylbenzo[c]thiophene
(7) as well as 1-thienyl-3-bithienylbenzo[c]thiophene (8)
were made by an analogous procedure as shown in
Scheme 2.
The substituted benzo[c]thiophenes 1-3 undergo the
Vilsmeier-Haack formylation readily to give the monoal-
dehydes 9-11, respectively. Dilithiation of 1-3 followed
by reaction with DMF and standard workup furnished
the dialdehydes 12-14 (Scheme 3).
† 1997 Summer High School Teacher Participant supported by
Epscor Grant No. DE-FCO2-91ER75678.
(1) Wegner, G.; Mu¨llen, K., Eds. Electronic Materials. The Oligomer
Approach; J ohn Wiley: New York, 1996.
(2) Goldoni, F.; Iarossi, D.; Mucci, A.; Schenetti, L. J . Chem. Soc.,
Chem. Commun. 1997, 2175.
(3) Tasaka, S.; Katz, H. E.; Hutton, R. S.; Orenstein, J .; Frederick-
son, G. H.; Wang, T. T. Synth. Met. 1989, 28, C729.
(4) Prasad, P. N.; Williams, D. J . Introduction to Nonlinear Optical
Effects in Molecules and Polymers; J ohn Wiley: New York, 1991.
(5) Salanek, W. R.; Bre´das, J . L. Solid State Commun. 1994, 92,
31.
(6) Hide, F.; Diaz-Garcia, M. A.; Schwartz, B. J .; Heeger, A. J . Acc.
Chem. Res. 1997, 30, 430.
(7) (a) Lorcy, D.; Cava, M. P. Adv. Mater. 1992, 4, 562. (b) Ba¨uerle,
P.; Go¨tz, G.; Emerle, P.; Port, H. Adv. Mater. 1992, 4, 564. (c)
Musinanni, S.; Ferraris, J . P. J . Chem. Soc., Chem. Commun. 1993,
172. (d) Kiebooms, R. H. L.; Adriaensens, P. J . A.; Vanderzande, D.
J . M.; Gelan, J . M. J . V. J . Org. Chem. 1997, 62, 1473.
Dithienylbenzo[c]thiophene (1) was converted readily
into the bispinacolboronate ester 15, which coupled with
S0022-3263(98)00246-1 CCC: $15.00 © 1998 American Chemical Society
Published on Web 04/16/1998

3106 J . Org. Chem., Vol. 63, No. 9, 1998
Mohanakrishnan et al.
Sch em e 2
Sch em e 4
Sch em e 5
Sch em e 3
(M+), and tetramer (17b) (M+). However, under con-
trolled conditions, dimer 16a can be isolated, albeit in
an impure state. Under the same conditions of oxidation,
2 gives a separable mixture of dimer 16b and trimer 17b
(Scheme 5). It is noteworthy that dimer 16 can be viewed
as a modified sexithiophene with enhanced solubility.
Similar results were obtained by oxidation of 3, which
gave 16c and 17c. The NMR spectra of 16b,c and 17b,c
are in accord with the assigned structures.
Dithienylbenzo[c]thiophene (1) was dilithiated and
treated with TBDMSCl to give the silyl derivative 18 in
96% yield (Scheme 6). In contrast to 1, silyl derivative
18 upon treatment with anhydrous ferric chloride fur-
nished only the dimer 19 in 66% yield. Treatment of 18
with titanium tetrachloride in DCM gave a mixture of
products from which chromatographic separation led only
to the isolation of the dimer 19.
2-bromothiophene in the presence of Pd0 to give 7 and 8
in 43% and 18% yield, respectively. In contrast, direct
coupling of lithiated 1 with 2-bromothiophene in the
presence of Ni(DPPP)Cl2 was not successful (Scheme 4).
Several years ago, we, as well as other investigators,
reported the electrochemical oxidation of 1 to a blue-black
polymer.7 In contrast, 2 and 3 do not deposit a dark film
upon electrochemical oxidation. Oxidation of 1 by an-
hydrous ferric chloride led to an insoluble dark powder.
Analysis by plasma desorption mass spectrometry re-
vealed the presence of a dimer (16a ) (M+), trimer (17a )
The monoaldehyde 9 and the dialdehyde 12 undergo
ready reaction with carbanions derived from malononi-
trile and arylmethylene and heteroarylmethylene nitriles
to give vinylene cyanides 20-24. They also undergo
Wittig reactions to give the vinylenes 25-29 (Scheme 7).

Studies in the Dithienylbenzo[c]thiophene Series
J . Org. Chem., Vol. 63, No. 9, 1998 3107
Sch em e 6
Sch em e 7
In contrast to the above carbanion reactions, the
carbanion derived from phosphonates leads mainly to an
unprecedented decarbonylation of 9. Subsequently, it
was found that aldehydes 9 and 12 undergo decarbony-
lation readily in the presence of sodium hydride in DMF
and potassium tert-butoxide in THF or DMF. Sodium
hydride in THF leads to recovery of 9. Apparently, strong
bases generate the acylanion, which loses carbon mon-
oxide. In the case of 12, decarbonylation occurs stepwise
as monitored by TLC (Scheme 8).
While the observed decarbonylation is mild and un-
precedented in the case of 9 and 12, under drastic
conditions, furfural is transformed into furan by molten
alkali.8
The aldehydes 9 and 12 were subjected to McMurray-
type coupling reaction conditions, but neither the dimer
30 nor the annulene 31 were identifiable in the intrac-
table mixture.
Ultr a violet Sp ectr a
The UV-vis spectra of the dithienylbenzo[c]thiophene
derivatives (Table 1) show an interesting pattern analo-
gous to that observed previously in the case of oligo-
thiophene derivatives. In contrast to terthiophene
CHCl3
max
(λ
, 355 nm) dithienylbenzo[c]thiophene (1) shows a
strong longest wavelength absorption at 433 nm (∆ ) 78
nm). The introduction of alkyl â-substituents (dodecyl
(8) Hurd, C. D.; Goldsby, A. R.; Osborne, E. N. J . Am. Chem. Soc.
1932, 54, 2532.

3108 J . Org. Chem., Vol. 63, No. 9, 1998
Mohanakrishnan et al.
Ta ble 2. F lu or escen ce Sp ectr a l Da ta
Sch em e 8
nm
excitation
nm
entry
compd
λ
λ
emission
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
1
2
3
4
7
433
412
412
285
485
460
473
453
452
491
458
458
483
483
498
500
451
519
558
503
510
587
560
478
514
511
550
532
531
528
533
604
575
592
578
579
571
569
569
600
582
622
637
547
593
677
549
655
686
676
606
640
624
8
9
10
11
12
13
14
16b
16c
17b
17c
18
19
20
21
22
23
24
26
27
28
29
Ta ble 1. UV-vis Sp ectr a l Da ta
CH2Cl2
max
entry
compd
λ
(nm) (log ꢀ)
1
2
3
4
5
6
1
2
3
4
18
7
217 (4.15), 232 (4.40), 286 (4.37), 433 (4.29)
232 (4.59), 412 (4.34)
217 (4.69), 234 (4.42), 281 (4.22), 411 (4.16)
284 (3.89), 433 (3.79)
217 (4.92), 232 (4.52), 296 (4.45), 446 (4.34)
218 (4.30), 231 (4.47), 308 (4.36), 361 (4.30),
482 (4.03)
7
8
217 (4.11), 233 (4.30), 254 (4.28), 291 (4.25),
458 (4.11)
1-4 and 17). The symmetrically benzannelated quin-
quithiophene 7 (Table 2, entry 5) emits light at 604 nm,
∼60-80 nm beyond the values for the terthiophene
analogues. The unsymmetrically annelated quater-
thiophene analogue 8 (Table 2, entry 6) emits light at
575 nm. Perusal of the λemission of the aldehydes shows a
similar pattern. The monoaldehydes 9-11 emit light at
592, 578, and 579 nm, respectively (Table 2, entries 7-9).
The dialdehydes 12-14 emit light ∼570 nm with much
less variation (Table 2, entries 10-12).
The derivatives 16b,c can be construed as alkyl-
substituted sexithiophenes with symmetrical annelation
of two benzene rings. Unlike the behavior of the ter-
thiophenes 2 and 3, 16b,c show an 18 nm difference in
their λemission (Table 2, entries 13 and 14). A similar
difference of ∼15 nm is seen in λemission in the trimeric
compounds 17b and 17c (Table 2, entries 15 and 16). The
aryl and heteroaryl cyanovinylenes 21 and 22 (Table 2,
entries 19 and 20) show a considerable shift (106 nm) in
the wavelength of emission. The absence of the cyano-
function in 26 produces a shift of almost 50 nm in its
emission (Table 2, entry 24) compared to 22 (Table 2,
entry 20). The difference in λemission between the dicy-
anovinylenes 20 and 23 (Table 2, entries 19 and 22) is a
modest 9 nm. In contrast to the vinylenes and cyanovi-
nylenes, the dicarbomethoxydithiolidene vinylene 29
shows no fluorescence whatsoever (Table 2, entry 27).
8
9
10
11
12
13
19
232 (4.57), 299 (4.38), 510 (4.62)
217, 235, 506
233 (4.57), 483 (5.0)
233 (4.75), 484 (4.76)
234 (4.99), 494 (5.0)
16a
16b
16c
17b
17c
236 (4.64), 502 (4.72)
and hexyl) into 1 lowers the long-wavelength absorption
to 412 and 411 nm, respectively, clearly indicative of the
twist in the backbone. When the R,R′ positions are
blocked by the TBDMS group, a bathochromic shift of
∼13 nm (433 nm f 446 nm) is induced, probably by the
dπ-pπ interaction due to the silicon. Comparison of the
published λmax for R,R′-TMS-substituted terthiophene
(368 nm)9 to that of 18 also shows a bathochromic shift
of 78 nm due to the annelation of the benzene ring. The
presence of a bromine at the R-position in 1 leads to no
change, whereas the presence of a methyl group increases
the λmax by 6 nm. Comparison of the longest absorption
band (458 nm) of 1-thienyl-3-bithienylbenzo[c]thiophene
(8) with that of quaterthiophene (390 nm)10 indicates a
strong red shift of 68 nm due to the annelation of the
benzene ring. The red shift in 7 (λmax, 482 nm) compared
to quinquethiophene (416 nm) is also 66 nm. Looking
at the dimers 16a and 16b, which can be viewed as
sexithiophenes, the long-wavelength bands are shifted
by 71 and 73 nm from the monomers 2 and 3. The dimer
derived from 1 also showed a red shift of 73 nm.
Cyclic Volta m m etr y
F lu or escen ce Sp ectr a
The cyclic voltammograms of the heterocycles (1-3, 7,
8, 16b,c, 18, and 19) were determined using a PAR model
263 instrument in dichloroethane containing 0.1 M
tetrabutylammonium hexafluorophosphate. The working
electrode (WE) was a Pt disk and the counter electrode,
Pt wire, the reference electrode being a standard calomel.
The data from these determinations are summarized in
Table 3. The following observations are pertinent. Tri-
heterocycle 1 is quickly polymerized to give a blue-black
deposit on the WE. In contrast, both 2 and 3 show an
Qualitative fluorescence spectra were recorded for a
number of compounds (Table 2). Compounds 1-4 and
18, which can be viewed as terthiophenes in which the
3,4-positions of the middle thiophene unit is annelated
to a benzene moiety, emit light in the 528-547 nm region
irrespective of the excitation wavelength (Table 2, entries
(9) Tour, J . M.; Wu, R. Macromolecules 1992, 25, 1901.
(10) Pham, C. V.; Burkhardt, A.; Shabana, R.; Cunningham, D. D.;
Mark, H. B., J r.; Zimmer, H. Phosphorus, Sulfur Silicon 1989, 46, 153.

Studies in the Dithienylbenzo[c]thiophene Series
J . Org. Chem., Vol. 63, No. 9, 1998 3109
Ta ble 3. Red ox Beh a vior of 1 a n d An a logu es
polymer/oligomer
entry
compd
pa1 (V)
pa2 (V)
pc1 (V)
pc2 (V)
formation
∆E1 (mV)
∆E2 (mV)
1
2
3
4
5
6
7
8
9
1
2
3
7
8
16b
16c
18
19
0.873a
0.94b
0.80a
yes
yes
yes
yes
yes
no
no
no
no
73
0.862b
0.724a
0.813b
0.730c
0.665c
0.830c
0.626c
1.13a
0.914a
1.055
0.8
100
76
1.008b
0.602c
0.734c
0.750c
0.705c
123
55
80
0.773c
0.756c
0.610c
0.565c
39
51
61
a
b
Quasireversible. Irreversible. c Reversible.
over anhydrous Na2SO4. All UV-vis spectra were recorded
irreversible peak at 0.94 and 0.86 V. No deposit was
observed on the Pt disk WE. However, the formation of
new electroactive species in 2 was discernible by the new
peaks at pa 0.650, 0.809 and pc 0.746, 0.612 V.
In the case of 3, the new electroactive species in
solution were detectable by the peaks at pa 0.561, 0.74
and pc 0.605 (broad). The authentic dimer 16b showed
broad reversible peaks at pa 0.730 and pc 0.602 V with
no change even after 50 scans. In the case of dimer 16c,
a pair of reversible peaks were seen at pa 0.665, 0.773
and pc at 0.734, 0.610 V.
The tetracycle 8, which can be viewed as a quater-
thiophene (E1/2 0.95 V irr) with one benzene ring anne-
lated to it, exhibits pa 0.813, 1.008 and pc 1.055 (br).
There is a quick change, and very soon new peaks appear
at pa 0.486, 0.677 and 0.815 V and pc shows a broad
signal centered around 0.5 V. There is a deposit on the
WE. The WE was washed free of soluble electroactive
species, and its CV was determined. It showed pa 0.789
and pc 0.6 V and was reversible.
The pentacycle 7 is a monobenzannelated quin-
quethiophene (E1/2 0.89 V irr) and shows peaks pa at
0.724, 1.13 V and pc at 0.914 and 0.8 V. In contrast to
the examples above, the silyl-capped terheterocycle 18
exhibits Coulombic reversibility, the peaks occurring at
pa 0.839 and pc at 0.765 V. The silylcapped dimeric
compound also shows Coulombic reversibility with peaks
at pa 0.626, 0.756 and pc at 0.705 and 0.565 V.
in CH2Cl2 solution.
2-Th ien yl p h th a lid e (5).7a,b An improved preparation of
5 is described below. A hot solution of 2-(2-thenoylbenzoic
acid) (30.0 g, 0.129 mol) in aqueous sodium bicarbonate (15.9
g in 2 L of H2O) was treated with NaBH4 (49.0 g, 1.29 mol) in
portions. After standing overnight, it was heated for 1 h on
the steam bath, cooled to room temperature, and then cau-
tiously acidified with 12% aqueous hydrochloric acid to pH 2.
The mixture was stirred for 2 h at room temperature, and the
white solid was filtered to give 5 (22.31 g, 80%).
1-(3-Dod ecylth ien yl)-3-th ien ylben zo[c]th iop h en e (2).
2-Bromo-3-dodecylthiophene (8 g, 0.024 mol) was added slowly
to a refluxing mixture of magnesium turnings (0.705 g, 0.029
mol) and iodine (20 mg) in dry THF. After the formation of
the Grignard reagent (6 h reflux), the cooled reagent was added
slowly via an addition funnel to a solution of lactone 5 in THF
(50 mL) at -10 °C. The reaction mixture was stirred for 6 h
at room temperature and was poured onto ice containing
NH4Cl. The intermediate was extracted into CH2Cl2 and dried
(Na2SO4), and the extract was treated with Lawesson’s reagent
(5 g, 0.012 mol) and was stirred at room temperature for 6 h.
Standard workup and filtration through a column of basic
alumina furnished 2 as a thick liquid (8.7 g, 77%): 1H NMR δ
7.95 (d, 1H, J ) 8.5 Hz), 7.55 (d, 1H, J ) 8.6 Hz), 7.38 (d, 2H,
J ) 5.2 Hz), 7.35 (d, 1H, J ) 3.3 Hz), 7.17-7.06 (m, 4H), 2.65
(t, 2H, J ) 7.8 Hz), 1.72-1.66 (m, 2H), 1.29-1.19 (m, 18H),
0.91 (t, 3H, J ) 5 Hz); MS 466 (M+, 100), 311 (36), 277 (24),
227 (47); UV-vis 412 (4.34), 232 (4.59). Anal. Calcd for
C
28H34S3: C, 72.03; H, 7.36; S, 20.61. Found: C, 71.97; H,
7.31; S, 20.49.
1-(3-Hexyl-2-th ien yl)-3-(2′-th ien yl)ben zo[c]th iop h en e
(3). The Grignard reagent from 2-bromo-3-hexylthiophene
was reacted with lactone 5 as described above. Workup
provided 3 (8 g, 64.5%) as an oil: 1H NMR δ 7.96 (d, 1H, J )
8.8 Hz), 7.55 (d, 1H, J ) 8.7 Hz), 7.38 (d, 2H, J ) 5.1 Hz),
7.38 (d, 1H, J ) 3.6 Hz), 7.16 (t, 1H, J ) 4.6 Hz), 7.11 (t, 1H,
J ) 5.4 Hz), 7.07 (d, 2H, J ) 5.4 Hz), 2.65 (t, 2H, J ) 7.9 Hz),
1.59 (q, 2H, J ) 7.4 Hz), 1.24 (m, 6H), 0.82 (t, 3H, J ) 7.1
Hz); MS 382 (M+, 100), 311 (55), 277 (41), 264 (36), 227 (92);
UV-vis 411 (4.16), 281 (4.22) 234 (4.42). Anal. Calcd for
C22H22S3: C, 69.05; H, 5.81; S, 25.14. Found: C, 68.96; H,
5.81; S, 25.06.
Con clu sion
The known 1,3,2-dithienylbenzo[c]thiophene (1) has
been functionalized to give a bis-TBDMS-capped trihet-
erocycle, vinylenes, cyanovinylenes, and dicyanovi-
nylenes. Several new â-alkyl-substituted analogues of
1 have been synthesized and characterized. Ferric
chloride oxidation of the triheterocycles has been carried
out, and the major products have been shown to be
dimeric molecules. The fluorescence spectra of the tri-,
tetra-, and pentaheterocycles have been recorded. The
results show that several heterocycles described above
may be suitable for the fabrication of LED devices. A
number of sexithiophene analogues incorporating specific
benzenoid annelation have been described. These could
find use in transistor11 applications by virtue of their
enhanced solubility compared to sexithiophene itself.
3-[2-(5-Br om oth ien yl)p h th a lid e] (5a ). A suspension of
pthalic anhydride (11.84 g, 0.08 mol) in CH2Cl2 (200 mL) was
treated with anhydrous AlCl3 (20 g, 0.15 mol). The mixture
was stirred for 0.5 h at room temperature and was treated
dropwise with a solution of 2-bromothiophene (15.6 g, 0.096
mol) in CH2Cl2 (100 mL). Standard workup yielded the 2-(5-
bromo-2-thenoyl)benzoic acid as a yellow solid (21 g; 84%): mp
1
158 °C; H NMR δ 8.07 (d, 1H, J ) 7.2 Hz), 7.65 (t, 1H, J )
7.6 Hz), 7.58 (t, 1H, J ) 7.4 Hz), 7.42 (d, 1H, J ) 7.2 Hz), 7.02
(d, 1H, J ) 3.96 Hz), 6.97 (d, 1H, J ) 4 Hz); MS 312 (M+2, 57),
310 (M+, 51), 230 (57), 223 (46), 110 (100). This intermediate
acid (9.96 g, 0.032 mol) was reduced as described for the
synthesis of 5 in hot sodium bicarbonate solution (4.77 g in
750 mL H2O) using NaBH4 (14.79 g, 0.388 mol). Yield of 5a
was 8.3 g (88.3%): mp 123 °C (crystallizes from MeOH or
Exp er im en ta l Section
All melting points are uncorrected. NMR spectra were
determined in CDCl3 solution containing TMS as internal
standard unless otherwise stated. Organic extracts were dried
1
hexane); H NMR δ 7.92 (d, 1H, J ) 7.1 Hz), 7.72 (t, 1H, J )
7.3 Hz), 7.61 (t, 1H, J ) 7.3 Hz), 7.45 (d, 1H, J ) 7.2 Hz), 6.95
(11) Horowitz, G.; Deloffre, F.; Garnier, F.; Hajlaoui, R.; Hmyene,
M.; Yassar, A. Synth. Met. 1993, 54, 435.

3110 J . Org. Chem., Vol. 63, No. 9, 1998
Mohanakrishnan et al.
(d, 1H, J ) 4.1 Hz), 6.85 (d, 1H, J ) 4.2 Hz), 6.55 (s, 1H).
Anal. Calcd for C12H7BrO2S: C, 48.84; H, 2.40; S, 10.87.
Found: C, 48.82; H, 2.36; S, 10.79.
Then it was passed through a column (Al2O3, 50% chloroform/
hexane) with a yield of 8 g (82.5%). A small amount of the
solid was recrystallized from methanol to give orange-red
needles: mp 112 °C (MeOH); 1H NMR 9.96 (s, 1H), 8.05 (t,
2H, J ) 7.4 Hz), 7.75 (d, 1H, J ) 7.2 Hz), 7.50-7.36 (m, 2H),
7.34-7.1 (m, 4H); MS 326 (M+, 100), 297 (26), 264 (26), 253
(27), 221 (10); UV-vis 474 nm (4.46), 293 (4.16), 239 (4.22).
Anal. Calcd for C17H10OS3: C, 62.54; H, 3.09; S, 29.47.
Found: C, 62.45; H, 3.06; S, 29.37.
1-(5-Br om ot h ien yl)-2-t h ien ylb en zo[c]t h iop h en e (4).
Thienylmagnesium bromide (from 2-bromothiophene 9) was
added to a solution of phthalide 5a (3 g, 0.01 mol) in THF at
-10 °C. After the addition was complete, the reaction mixture
was stirred at room temperature for 2 h, poured over ice-cooled
NH4Cl solution, and extracted with methylene chloride (3 ×
40 mL). The solution was treated with Lawesson’s reagent
(2.1 g, 0.01 mol) and stirred at room temperature for 4 h.
Methylene chloride was removed, and the residue was gently
heated (fume hood) on a steam bath with ethanol (40 mL). The
crude product was adsorbed on alumina (neutral) and placed
in a Soxhlet apparatus, and the product was extracted using
hexane as eluent: yield 1.6 g (42.1%); mp 90 °C (methanol);
1H NMR δ 7.96 (d, 1H, J ) 3.5 Hz), 7.95 (d, 1H, J ) 3.6 Hz),
7.39-7.35 (m, 3H), 7.16-7.13 (m, 4H); MS 378 (M+1, 30), 377
(M+, 31), 298 (100), 264 (30), 253 (30), 221 (42); UV-vis 433
(3.79), 284 (3.89); HRMS calcd for C16H9BrS3 377.9029, found
377.9038.
Ald eh yd e 10. Substrate 2 (5.5 g, 0.0118 mol) was reacted
with the Vilsmeier reagent prepared from DMF (1.2 mL,
0.0155 mol) and POCl3 (1.4 mL, 0.015 mol) as described for 9
to yield after workup product 10 (5.3 g; 91%) as a thin liquid:
1H NMR δ 9.91 (s, 1H), 8.06 (d, 1H, J ) 8.9 Hz), 7.77 (d, 1H,
J ) 4 Hz), 7.62 (d, 1H, J ) 8.8 Hz), 7.44 (d, 1H, J ) 4.1 Hz),
7.43 (d, 1H, J ) 5.6 Hz), 7.27 (t, 1H, J ) 6.8 Hz), 7.18 (t, 1H,
J ) 8.9 Hz), 7.08 (d, 1H, J ) 5.2 Hz), 2.65 (t, 2H, J ) 7.6 Hz),
7.59 (m, 2H), 1.20 (m, 18), 0.87 (t, 3H, J ) 6.9 Hz); MS 494
(M+, 100), 466, 339 (55), 277 (26), 244 (20), 227 (70); UV-vis
453 (4.44), 237 (4.48). Anal. Calcd for C29H34OS3: C, 70.38;
H, 6.94; S, 19.44. Found: C, 70.42; H, 6.96; S, 19.31.
Ald eh yd e 11. This was prepared in a similar manner using
POCl3 (0.32 mL, 3.4 mmol), DMF (0.26 mL, 3.4 mmol), and 3
(1.0 g, 2.62 mmol). After workup, it was obtained as a thin
liquid (0.85 g; 79%): 1H NMR δ 9.84 (s, 1H), 7.98 (d, 1H, J )
8.8 Hz), 7.69 (d, 1H, J ) 4 Hz), 7.53 (d, 1H, J ) 8.4 Hz), 7.36
(d, 1H, J ) 4.3 Hz), 7.35 (d, 1H, J ) 5.5 Hz), 7.19 (t, 1H, J )
6.6 Hz), 7.07 (t, 1H, J ) 6.7 Hz), 7.01 (d, 1H, J ) 53 Hz), 2.57
(t, 2H, J ) 7.9 Hz), 1.51 (q??, 2H, J ) 7.2 Hz), 1.17 (m, 6H),
0.74 (t, 3H, J ) 6.9 Hz); MS 410 (M+, 86), 339 (69), 298 (26),
277 (58), 227 (100); UV-vis 4.53 (4.31), 236 (4.36), 217 (4.19).
Anal. Calcd for C23H22OS3: C, 67.26; H, 5.41; S, 23.42.
Found: C, 66.99; H, 5.37; S, 23.18.
1,3-Di(2-th ien yl)ben zo[c]th iop h en e-5,5′-d ica r boxa ld e-
h yd e (12). A solution of 1 (5 g, 0.0168 mol) and TMEDA (10.1
mL, 0.067 mol) in dry THF (150 mL) was cooled to -78 °C
under N2 and was treated with a solution of n-BuLi (50 mL, 2
M). The temperature was slowly raised to 0 °C, and the
mixture was stirred at that temperature for 1 h. The mixture
was recooled to -78 °C and was treated with dry DMF (45
mL, 0.58 mol). The mixture was then stirred at room tem-
perature for 12 h and poured into crushed ice containing HCl.
The precipitate of 12 was filtered after stirring for 2 h, washed
with water, and dried in vacuo to give 5.2 g (87.5% yield): mp
241 °C (crystallized from toluene); 1H NMR δ 9.93 (s, 2H), 8.09
(d, 1H, J ) 3.6 Hz), 8.07 (d, 1H, J ) 3.6 Hz), 7.80 (d, 2H, J )
3.6 Hz), 7.49 (d, 2H, J ) 3.6 Hz), 7.33 (d, 1H, J ) 3.5 Hz),
7.31 (d, 1H, J ) 3.1 Hz); MS 354 (M+, 100), 326 (3.3), 281
(10.9), 239 (34.7); UV-vis 491 (4.63), 304 (4.32), 232 (4.52),
217 (4.37). Anal. Calcd for C18H10O2S3: C, 60.98; H, 2.85; S,
27.14. Found: C, 61.45; H, 2.93; S, 27.24.
1-(3-Dodecyl-2-th ien yl)-3-(2′-th ien yl)ben zo[c]th ioph en e-
5,5′-d ica r boxa ld eh yd e (13). A solution of substrate 2 (1 g,
2.1 mmol) and TMEDA (0.81 mL, 5.35 mmol) in 30 mL of dry
THF was cooled to -78 °C under N2 and was treated with 2.3
mL of 2.4 M n-BuLi. The mixture was stirred at the same
temperature for 2 h, and DMF (1 mL) was added to the orange-
red solution. The temperature was slowly raised to room
temperature, and the mixture was stirred for 30 min. It was
then poured over crushed ice and HCl, stirred for 2 h, extracted
with ether, and dried (Na2SO4). It was then passed through
a column of alumina to get 13 as a dark red liquid with a yield
of 0.85 g (75.8%): 1H NMR δ 9.94 (s, 1H), 9.92 (s, 1H), 8.08 (d,
1H, J ) 8.9 Hz), 7.79 (d, 1H, J ) 4 Hz), 7.75 (s, 1H), 7.69 (d,
1H, J ) 8.8 Hz), 7.48 (d, 1H, J ) 4 Hz), 7.31 (t, 1H, J ) 8.7
Hz), 7.23 (t, 1H, J ) 8.7 Hz), 2.73 (t, 2H, J ) 7.5 Hz), 1.64 (t,
2H, J ) 7.4 Hz), 1.23 (m, 18H), 0.87 (t, 3H, J ) 7 Hz); MS 522
(M+, 100), 494 (53), 367 (43), 337 (24), 309 (23), 277 (25), 255
(38), 227 (39); UV-vis 460 (4.47), 303 (4.26), 236 (4.44). Anal.
Calcd for C30H34O2S3: C, 68.91; H, 6.57; S, 18.40. Found: C,
68.97; H, 6.64; S, 18.31.
3-(2-Bith ien yl)p h th a lid e (5b). The bithenoyl benzoic acid
(12 g) was made from 2,2′-bithiophene (8.4 g, 0.051 mol) and
phthalic anhydride (7.5 g, 0.051 mol) in CH2Cl2 in 76% yield:
mp 161 °C; 1H NMR δ 8.08 (d, 1H, J ) 7.8 Hz), 7.65 (t, 1H, J
) 7.5 Hz), 7.56 (t, 1H, J ) 7.5 Hz), 7.57 (d, 1H, J ) 7.4 Hz)
7.35 (s, 1H), 7.32 (d, 1H, J ) 4.3 Hz), 7.14 (d, 1H, J ) 3.9 Hz),
7.09 (d, 1H, J ) 4 Hz), 7.05 (t, 1H, J ) 4.4 Hz).
The above acid was reduced to phthalide 5b in 77% yield
by a procedure similar to that of 3-thienylphthalide: mp 164
1
°C; H NMR δ 7.97 (d, 1H, J ) 7.7 Hz), 7.74 (t, 1H, J ) 7.3
Hz), 7.61 (t, 1H, J ) 7.6 Hz), 7.50 (d, 1H, J ) 7.1 Hz), 7.22 (d,
1H, J ) 4.1 Hz), 7.12 (d, 1H, J ) 4.1 Hz), 7.08 (m, 2H), 6.99
(m, 1H), 6.62 (s, 1H); MS 298 (M+, 100), 254 (41), 253 (52),
221 (30); UV-vis 217 (4.15), 232 (4.40), 286 (4.37), 433 (4.29).
Anal. Calcd for C16H10O2S2: C, 64.40; H, 3.38; S, 21.49.
Found: C, 64.29; H, 3.33; S, 21.53.
1,3-(Dibit h ien yl)b en zo[c]t h iop h en e (7). A solution of
bithiophene (1.67 g, 0.01 mol) in dry THF (100 mL) was treated
with n-BuLi (4 mL, 2.5 M) and TMEDA (1.5 mL, 0.01 mol) at
-78 °C under N2. The temperature was slowly raised to 0 °C
and stirred for 30 min. Then it was slowly added to a solution
of lactone 5b (1.5 g, 0.005 mol) in dry THF (50 mL) at -10 °C.
After the addition was complete, the reaction mixture was
stirred at room temperature for 1 h, poured over ice-cooled
NH4Cl solution, and extracted with methylene chloride (3 ×
50 mL). The solution was treated with Lawesson’s reagent (1
g) followed by conventional workup, and column chromatog-
raphy separation on basic alumina (hexane) gave 7: 0.8 g
1
(35%); mp 175 °C; H NMR δ 8 (d, 1H, J ) 2.8 Hz), 7.98 (d,
1H, J ) 2.8 Hz), 7.35-7.15 (m, 10H), 7.05 (t, 2H, J ) 4.4 Hz);
MS 462 (M+, 95), 335 (11), 231 (19); UV-vis 482 (4.03), 361
(4.30), 308 (3.46), 231 (4.47), 218 (4.30). Anal. Calcd for
C
24H14S5: C, 62.29; H, 3.06; S, 34.65. Found: C, 6237; H, 3.06
S, 34.52.
1-Bith ien yl-3-th ien ylben zo[c]th iop h en e (8). Reaction
of 2-thienylmagnesium bromide from 2-bromothiophene (0.82
g, 5.0 mmol) with phthalide 5b (1.0 g, 3.3 mmol) followed by
workup and thionation with Lawesson’s reagent (0.7 g) led to
8: 0.5 g (39%); mp 94 °C; 1H NMR δ 7.94 (m, 2H), 7.39 (d, 1H,
J ) 51. Hz), 7.35 (d, 1H, J ) 3.6 Hz), 7.26 (d, 1H, J ) 3.6 Hz),
7.23 (d, 1H, J ) 3.6 Hz), 7.2 (d, 1H, J ) 3.7 Hz), 7.16 (m, 4H),
7.05 (m, 1H); MS 380 (M+, 100), 335 (15), 253 (12), 190 (32);
UV-vis 458 (4.11), 291 (4.25), 254 (4.28), 233 (4.30), 217 (4.11).
Anal. Calcd for C24H14S5: C, 63.11; H, 3.18; S, 33.70. Found:
C, 63.01; H, 3.19; S, 33.62.
Ald eh yd e 9. POCl3 (2.96 mL, 0.032 mol) was slowly added
to a mixture of CH2Cl2 (40 mL) and DMF (2.45 mL, 0.032 mol)
at 0 °C. After the addition was over, the mixture was stirred
at room temperature until a pale yellow color formed. It was
then added to 1 (9 g, 0.03 mol) dissolved in CH2Cl2 (50 mL) at
0 °C. The reaction mixture was stirred at room temperature
for 10 h, and the solvent was completely removed. Aqueous
NaOH was added, the mixture was heated on a steam bath
for 1 h and cooled, and the product was filtered and air-dried.
1-(3-Hexyl-2-th ien yl)-3-(2′-th ien yl)ben zo[c]th iop h en e-
5,5′-d ica r boxa ld eh yd e (14). Dialdehyde 14 was prepared
exactly as described above from substrate 3 (1.0 g, 2.6 mmol),
n-BuLi (2.84 mL, 6.8 mmol), TMEDA (1.1 mL, 6.8 mmol), and

Studies in the Dithienylbenzo[c]thiophene Series
J . Org. Chem., Vol. 63, No. 9, 1998 3111
DMF (1 mL) as a red liquid (0.84 g, 73%): 1H NMR δ 9.94 (s,
1H), 9.92 (s, 1H), 8.07 (d, 1H, J ) 8.8 Hz), 7.8 (d, 1H, J ) 3.9
Hz), 7.75 (s, 1H), 7.7 (d, 1H, J ) 8.8 Hz), 7.48 (d, 1H, J ) 4.1
Hz), 7.31 (t, 1H, J ) 6.7 Hz), 7.23 (t, 1H, J ) 6.9 Hz), 2.73 (t,
2H, J ) 7.6 Hz), 1.64 (d, 2H, J ) 6.7 Hz), 1.2 (m, 6H), 0.83 (t,
3H, J ) 6.8 Hz); MS 438 (M+, 93), 410 (100), 367 (33), 339
(46), 227 (90); UV-vis 459 (4.65), 268 (4.57), 235 (4.60), 217
(4.50). Anal. Calcd for C24H22O2S3: C, 65.71; H, 5.06; S, 21.93.
Found: C, 65.60; H, 5.12; S, 22.01.
1,3-[5,5′-Bis-(ter t-bu tyld im eth ylsilyl)-2,2′-th ien yl]ben -
zo[c]th iop h en e (18). Dilithiation of 1 (1.0 g, 3.36 mmol) in
dry THF (50 mL) was carried out as described earlier using
n-BuLi (3.9 mL, 2.4 M) and TMEDA (1.52 mL, 9.4 mmol). A
solution of tert-butyldimethylsilyl chloride (1.6 g, 10.6 mmol)
in dry THF (15 mL) was added to the cooled (-78 °C)
dilithiation mixture. The cooling bath was removed, and the
mixture was stirred and was slowly warmed to room temper-
ature (1/2 h). Workup and chromatography of the crude
product on basic alumina (hexane eluant) led to the isolation
Bis-bor ola n e (15). The dilithiation of 1 (1 g, 3.36 mol) was
carried out as described previously, pinacol boronate (3.4 mL,
0.022 mol) was added, and the mixture was stirred for 10 h.
Workup led to the isolation of a sticky residue that was
triturated with methanol to give a solid (0.9 g; 52.8%): mp
1
of 18 (1.7 g, 96%): mp 107 °C; H NMR 8.01 (d, 1H, J ) 3.2
Hz), 7.99 (d, 1H, J ) 2.9 Hz), 7.43 (d, 2H, J ) 3.5 Hz), 7.26 (d,
2H, J ) 3.5 Hz), 7.16 (d, 1H, J ) 3 Hz), 7.14 (d, 1H, J ) 2.9
Hz), 0.99 (s, 18 H), 0.36 (s, 12H); UV-vis 446 (4.34), 296 (4.45),
232 (4.52), 217 (4.42). Anal. Calcd for C28H38S3Si2: C, 63.80;
H, 7.28; S, 18.25. Found: C, 63.90; H, 7.27; S, 18.15.
1
162 °C; H NMR δ 8.06 (d, 1H, J ) 3.1 Hz), 8.04 (d, 1H, J )
3 Hz), 7.65 (d, 1H, J ) 3.7 Hz), 7.43 (d, 1H, J ) 3.6 Hz), 7.17
(d, 1H, J ) 2.2 Hz), 7.15 (d, 1H, J ) 3.1 Hz), 1.37 (s, 24 H);
MS 550 (M+, 23), 424 (56), 298 (99), 274 (100); HRMS calcd
for B2C28H32O4S3 548.1721, found 548.1712.
Dim er iza tion of 18 To Give 19. Oxidative dimerization
of 18 (0.1 g, 0.19 mmol) in CH2Cl2 (20 mL) with anhydrous
FeCl3 (0.035, 0.21 mmol) was carried out as described before.
Dimer 19 (0.031 g; 66%) based on recovered starting material)
Su zu k i Cou p lin g of Bor ola n e (15) w it h 2-Br om o-
th iop h en e. A solution of borolane 15 (0.16 g, 0.3 mmol) and
2-bromothiophene (0.12 mL, 1.2 mmol) in dry DMF (10 mL)
was treated with tetrakis(triphenylphosphine)palladium (0.05
g, 0.4 mmol) and K3PO4 (0.39 g, 1.83 mmol) at 110 °C. The
mixture was maintained at the same temperature for 24 h
under N2 and poured over 200 mL of H2O. Extraction with
methylene chloride followed by chromatography on basic
alumina (40:1 hexane-CH2Cl2 f 20:1 hexane-CH2Cl2) yielded
compound 7 (0.06 g, 43%) and compound 8 (0.02 g, 18%).
F er r ic Ch lor id e Oxid a tion of (1). A solution of 1 (0.5 g,
1.68 mmol) in CH2Cl2 (40 mL) was treated with anhydrous
FeCl3 (0.31 g, 1.8 mmol) under nitrogen. The mixture was
stirred at room temperature for 6 h and diluted with more
CH2Cl2 (50 mL). The dark mixture was treated with a dilute
solution of NH2NH2‚H2O. Evaporation afforded a dark powder
containing 16a .
1
was isolated: mp 186 °C; H NMR 8.01 (m, 4H), 7.44 (d, 2H,
J ) 3.5 Hz), 7.3 (d, 2H, J ) 3.8 Hz) 7.28-7.25 (m, 6H), 7.18 (t,
4H, J ) 4.4 Hz); UV-vis 510 (4.62), 299 (4.38), 232 (4.57).
Anal. Calcd for C44H46S6Si2: C, 64.17; H, 5.74; S, 23.37.
Found: C, 64.27; H, 5.67; S, 23.27.
Cya n ovin ylen e 20. A mixture of monoaldehyde 9 (0.1 g,
0.31 mmol), malononitrile (0.05 g, 0.76 mmol), and â-alanine
(0.03 g, 0.33 mmol) in dry THF (50 mL) was refluxed for 24 h.
The solvent was removed, water was added, and the solid (20)
was filtered, washed with more water and methanol, and dried
1
(0.08 g; 70.2%): mp 178 °C; H NMR δ 8.05 (d, 1H, J ) 3.9
Hz), 8.03 (d, 1H, J ) 3.9 Hz), 7.76 (s, 1H), 7.71 (d, 1H, J ) 4.1
Hz), 7.69-7.45 (m, 3H), 7.36 (t, 1H, J ) 8.9 Hz), 7.26 (m, 1H),
7.19 (t, 1H, J ) 4.7 Hz); MS 374 (M+, 100), 329 (11), 253 (8%),
208 (8), 187 (17); UV-vis 555 (4.25), 297 (3.98), 231 (4.04).
Anal. Calcd for C20H10N2S3‚0.25CH3OH: C, 63.58; H, 2.90;
N, 7.32; S, 25.15. Found: C, 63.49; H, 2.74; N, 7.18; S, 25.23.
F er r ic Ch lor id e Oxid a tion of 2 To Give 16b a n d 17b.
The oxidation of 2 (0.6 g, 1.1 mmol) was carried out in CH2Cl2
as described above using anhydrous FeCl3 (0.191 g, 1.2 mmol).
After workup, the residue from CH2Cl2 was resolved by
chromatography (SiO2; hexane-CH2Cl2 10:1) to give unreacted
2 (0.2 g), dimer 16b (0.25 g; 62.5% based on recovered starting
material) as a thin red oil and trimer 17b, also an oil (0.05 g,
12.5): 1H NMR spectrum of 16b δ 7.95 (d, 2H, J ) 8.9 Hz),
7.5 (d, 2H, J ) 8.8 Hz), 7.31 (d, 2H, J ) 5.2 Hz), 7.22 (d, 2H,
J ) 3.8 Hz), 7.18 (d, 2H, J ) 3.8 Hz), 7.10 (t, 2H, J ) 8.5 Hz),
7.02 (t, 2H, J ) 8.5 Hz), 6.99 (d, 2H, J ) 5.4 Hz), 2.58 (t, 4H,
J ) 7.5 Hz), 1.52 (m, 4H), 1.15 (m, 36 H), 0.79 (t, 6H, J ) 6.93
Hz); PDMS spectrum 931.5 (M+); UV-vis 483 (4.59), 233
Cya n ovin ylen e 21. A mixture of aldehyde 9 (0.2 g, 0.61
mmol) and 4-piperonylmethyl cyanide (0.197 g, 1.2 mmol) was
added to a stirred suspension of NaH (0.059 g) in dry THF
(50 mL). The mixture was quenched with NH4Cl solution after
being stirred for 10 h at room temperature. The solvent was
removed, and the solid 21 was filtered and washed with
1
methanol: mp 184-185 °C; H NMR δ 8.04 (d, 1H, J ) 8.8
Hz), 7.98 (d, 1H, J ) 8.7 Hz), 7.50 (d, 1H, J ) 41 Hz), 7.49 (s,
1H), 7.42-7.37 (m, 3H), 7.23-7.15 (m, 4H), 7.11 (d, 1H, J )
1.8 Hz), 6.87 (d, 1H, J ) 8.1 Hz), 6.03 (s, 2H); MS 469 (M+,
30.6), 206 (61), 195 (48), 189 (49), 121 (100); UV-vis 499 (4.44),
383 (4.05), 290 (4.27), 231 (4.35). Anal. Calcd for
1
(4.57); H NMR spectrum of 17b δ 8.06-7.57 (m, 6H), 7.41-
C
26H15N2O2S3: C, 66.49; H, 3.23; N, 2.98; S, 20.49. Found:
4.39 (d, 2H, J ) 5.2 Hz), 7.32-7.11 (m, 13H), 7.08-7.07 (d,
2H, J ) 5.2 Hz), 2.69-2.66 (m, 6H), 1.68-1.58 (m, 6H), 1.56-
1.49 (m, 54H), 10.80-0.77 (m, 9H); MS 1396.6 (M+); UV-vis
494 (5.0), 234 (4.99). Anal. Calcd for C56H66S6: C, 72.19; H,
7.15; S, 20.65. Found: C, 71.98; H, 7.17; S, 20.41.
C, 66.27; H, 3.25; N, 2.89; S, 20.33.
Cya n ovin ylen e 22. Aldehyde 9 (0.25 g, 0.77 mmol) was
condensed with thiopheneacetonitrile (0.19 g, 1.5 mmol) in the
presence of NaH (0.15 g) in dry THF (40 mL) as described
above. Workup led to the isolation of 22 (0.3 g, 91% yield):
F er r ic Ch lor id e Oxid a tion of 3 To Give 16c a n d 17c.
Oxidation of 3 (0.5 g, 1.3 mmol) with anhydrous FeCl3 (0.22 g,
1.3 mmol) followed by reductive workup as described above
led to the isolation of 16c as an oil (0.15 g; 43%)-based
recovered starting material as well as 17c (0.08 g; 23%), also
an oil: 1H NMR spectrum 16c δ 8.01 (d, 2H, J ) 8.8 Hz), 7.57
(d, 2H, J ) 8.8 Hz), 7.39 (d, 2H, J ) 5.2 Hz), 7.29 (d, 2H, J )
3.7 Hz), 7.27 (d, 2H, J ) 3.8 Hz), 7.18 (t, 2H, J ) 8.8 Hz), 7.1
(t, 2H, J ) 8.8 Hz), 7.07 (d, 2H, J ) 5.3 Hz), 2.66 (t, 4H, J )
7.3 Hz), 1.59 (q, 4H, J ) 6.8 Hz), 1.22 (m, 12H), 0.82 (t, 6H, J
) 6.4 Hz); MS 762 (M+), 728, 548 (11), 382 (100), 314 (45);
UV-vis 484 (4.76), 233 (4.75), 217 (4.51). Anal. Calcd for
1
mp 161 °C; H NMR δ 0.03 (d, 1H, J ) 8.6 Hz), 797 (d, 1H, J
) 8.6 Hz), 7.57 (d, 1H, J ) 3.4 Hz), 7.44 (s, 1H), 7.41 (d, 1H,
J ) 5 Hz), 7.37 (m, 2H), 7.39 (d, 1H, J ) 2.5 Hz), 7.28 (d, 1H,
J ) 4.7 Hz), 7.25 (d, 1H, J ) 5.4 Hz), 7.21 (d, 1H, J ) 4.3 Hz),
7.17 (d, 1H, J ) 5 Hz), 7.07 (t, 1H, J ) 3.9 Hz); MS 431 (M+,
62), 386 (36), 365 (50), 253 (49), 215 (100), 149 (81); UV-vis
506 (4.48), 291 (4.26), 231 (4.35). Anal. Calcd for C23H13NS4:
C, 63.99; H, 3.09; N, 3.25; S, 29.72. Found: C, 63.73; H, 3.21;
N, 3.41; S, 29.47.
Bis(cya n ovin ylen e) 23. A mixture of dialdehyde 12 (0.4
g, 1.13 mmol), malononitrile (0.3 g, 4.5 mmol), and â-alanine
(0.1 g) in dry THF (100 mL) was refluxed for 2 h. Workup led
to the isolation of 23 (0.45 g, 88.6%): mp >350 °C; 1H NMR δ
8.15 (d, 1H, J ) 3 Hz), 8.09 (d, 1H, J ) 3.9 Hz), 7.82 (s, 2H),
7.78 (d, 2H, J ) 4.3 Hz), 7.57 (d, 2H, J ) 4.1 Hz), 7.44 (d, 1H,
J ) 3.9 Hz), 7.42 (d, 1H, J ) 2.8 Hz); MS 450 (M+, 100), 431
(27), 149 (75); UV-vis 590 (4.61), 354 (4.06), 251 (4.14). Anal.
Calcd for C24H10N4S3: C, 63.97; H, 2.24; N, 12.44; S, 21.35.
Found: C, 63.96; H, 2.23; N, 12.34; S, 21.27.
C
44H42S6: C, 69.23; H, 5.56; S, 25.21. Found: C, 69.31: H,
5.58; S, 25.07; 1H NMR spectrum 17c δ 8.04-7.57 (m, 6H),
7.41-7.39 (d, 2H, J ) 4.9 Hz), 7.29-7.11 (m, 13H), 7.09-7.07
(d, 2H, J ) 5.2 Hz), 2.68-2.64 (t, 6H, J ) 7.2 Hz), 1.67-1.58
(m, 6H), 1.25-1.22 (m, 18H), 0.85-0.81 (t, 9H, J ) 6.5 Hz);
UV-vis 502 (4.72), 236 (4.64).
66H62S9‚H2O: C, 68.22; H, 5.56; S, 24.84. Found: C, 68.32;
H, 5.53; S, 24.84.
Anal.
Calcd for
C

3112 J . Org. Chem., Vol. 63, No. 9, 1998
Mohanakrishnan et al.
Bis(cya n ovin ylen e) 24. Dialdehyde 12 (0.1 g, 0.28 mmol)
was condensed with 2-thiopheneacetonitrile (0.14 g, 1.13
mmol) in THF solution in the presence of NaH (0.05 g, 2.1
mmol). The crude product isolated after workup was extracted
from a Soxhlet cup using CHCl3 to give pure 24 (0.14 g,
7.9-7.3 (m, 4H), 7.25-7 (m, 12H); MS 514 (M+), 277 (100);
UV-vis 514 (4.46), 357 (4.48); HRMS calcd for C28H18S5
514.0012, found 514.000.
Bis(p h en ylen evin ylen e) 28. A suspension of anhydrous
K2CO3 (1 g), benzyltriphenylphosphonium chloride (0.3 g, 0.77
mmol), and dialdehyde 12 (0.1 g, 0.282 mmol) in dry MeCN
was stirred at room temperature for 10 h. The solvent was
removed, and water was added. The precipitate of 28 was
washed with water and methanol. It was purified via filtration
through a column of Al2O3 (2:3 chloroform-hexane eluant) to
give pure 28 (0.13 g, 86%): mp 172 °C; 1H NMR δ 8.05 (d, 1H,
J ) 2.1 Hz), 8.03 (d, 1H, J ) 3.9 Hz), 7.51 (d, 4H, J ) 10.1
Hz), 7.37 (t, 4H, J ) 7.92 Hz), 7.27 (m, 5H), 7.19 (m, 3H), 7.09
(d, 2H, J ) 3.96 Hz), 6.99-6.95 (d, 2H, J ) 16.2 Hz); MS 502
(M+, 100), 341 (38), 211 (31), 207 (32), 156 (63); UV-vis 510
(4.61), 348 (4.57), 275 (4.51), 241 (4.47). Anal. Calcd for
C32H22S3: C, 76.44; H, 4.42; S, 19.14. Found: C, 76.19; H,
4.35; S, 18.99.
1
87.5%): mp 222 °C; H NMR δ 8.08 (d, 1H, J ) 3.5 Hz), 8.07
(d, 1H, J ) 3.42), 7.6 (d, 2H, J ) 3.96 Hz), 7.67 (s, 2H), 7.42
(d, 2H, J ) 4 Hz), 7.36 (d, 2H, J ) 3.53 Hz), 7.28 (m, 4H), 7.08
(t, 2H, J ) 4.3 Hz); MS 564 (M+, 100), 563 (84), 502 (16), 282
(11), 211 (14), 169 (11); UV-vis 555 (4.58), 422 (3.97), 267
(4.06), 296 (3.98), 244 (4.03).
30H16N2S5‚0.75CHCl3: C, 56.44; H, 2.58; N, 4.28; S, 24.50.
Found: C, 56.57; H, 2.58; N, 4.27; S, 24.47.
Anal.
Calcd for
C
1,3-Dith iolid en e Der iva tive 25. Monoaldehyde 9 (0.2 g,
0.61 mmol) was condensed with 1,3-dithiolyl-4,5-dicarbomethox-
yphosphonium tetrafluoroborate (0.62 g, 1.2 mmol) in the
presence of Et3N (2 mL) in CH2Cl2 solution (40 mL) to give 25
1
as a red solid (0.21 g, 64.8%): mp 122 °C; H NMR δ 7.98-
7.94 (m, 2H), 7.39-7.36 (m, 2H), 7.30 (d, 1H, J ) 3.6 Hz),
7.17-7.14 (m, 3H), 6.91 (d, 1H, J ) 3.7 Hz), 6.67 (s, 1H), 3.89
(s, 3H), 3.88 (s, 3H); MS 528 (M+, 100), 494 (11), 470 (9), 382
(25), 354 (36), 309 (41), 277 (40), 227 (56); UV-vis 485 (4.46),
368 (4.11), 232 (4.38). Anal. Calcd for C24H16O4S: C, 54.51;
H, 3.06; S, 30.33. Found: C, 54.66; H, 3.08; S, 30.20.
Bis(4,5-d ica r bom et h oxy-1,3-d it h iolid en e) Der iva t ive
29. A mixture of (4,5-dicarbomethoxy-1,3-dithiolyl)triphe-
nylphosphonium tetrafluoroborate (2.8 g, 0.0056 mol) and
dialdehyde 12 (0.5 g, 0.0014 mol) in CH2Cl2 (250 mL) was
treated with Et3N (5 mL). The orange solution turned purple.
After 4 h at room temperature, the volatile material was
removed in vacuo and the residue was triturated with MeOH
to give 29 (1 g, 93.4%): mp 238 °C; 1H NMR δ 7.98 (d, 1H, 2.9
Hz), 7.96 (d, 1H, J ) 3.24 Hz), 7.30 (d, 2H, J ) 3.9 Hz), 7.19
(d, 1H, J ) 2.95 Hz), 7.13 (d, 1H, J ) 3.04 Hz), 6.92 (d, 2H, J
) 3.96 Hz), 6.67 (s, 2H), 3.89 (s, 3H), 3.88 (s, 3H); UV-vis
528 (4.52), 397 (4.30), 234 (4.48). Anal. Calcd for
Th ien ylen evin ylen e 26. Monoaldehyde 9 (0.33 g, 1 mmol)
was condensed with (2-thienylmethyl)triphenylphosphonium
bromide (0.88 g, 2 mmol) in the presence of NaH (0.06 g, 2.5
mmol) in dry THF (40 mL) to give after standard workup
1
vinylene 26 (0.1 g, 25%): mp 94 °C; H NMR δ 8.02-8 (dd,
1H), 7.97-7.94 (dd, 1H), 7.38 (d, 1H, J ) 5 Hz), 7.36 (d, 1H, J
) 3.4 Hz), 7.24 (d, 1H, 5.1 Hz), 7.2 (d, 1H, J ) 5.1 Hz), 7.17-
7.14 (m, 3H), 7.06 (d, 2H, J ) 6.3 Hz), 7.04 (d, 1H, J ) 3.9
Hz), 7.02-7 (m, 2H); MS 406 (M+, 100), 372, 340, 277, 253,
203; UV-vis 478 (4.23), 358 (4.26), 291 (4.30), 232 (4.30), 217
(4.17). Anal. Calcd for C22H14S4: C, 64.98; H, 3.48; S, 31.55.
Found: C, 64.92; H, 3.46; S, 31.45.
C
32H22O8S7: C, 50.63; H, 2.93; S, 29.58. Found: C, 50.81; H,
2.90; S, 29.48.
Ack n ow led gm en t. This work was supported by a
grant from the National Science Foundation (CHE-
9612350). We thank Dr. J an Becher and K. Simonsen,
Odense University, Denmark, for PDMS determina-
tions. We also thank Dr. Ken Belmore, The University
of Alabama, for help with NMR spectral analysis.
Bis(th ien ylen evin ylen e) 27. A mixture of dialdehyde 12
(0.2 g, 0.56 mmol) and (2-thienylmethyl)triphenylphosphonium
bromide (0.745 g, 1.7 mmol) was added to a suspension of NaH
(0.061 g) in dry THF (100 mL) and was stirred for 2 days at
room temperature. Standard workup afforded 27 as black
1
powder (0.25 g, 86%): mp 92 °C; H NMR δ 8.02-8 (m, 2H),
J O980246A