Synthesis and characterization of 9,9-dialkylfluorene capped benzo[c]thiophene/benzo[c]selenophene analogs as potential OLEDs

Article abstract of DOI:10.1016/j.tetlet.2008.05.107

The synthesis of soluble benzo[c]thiophene analogs capped with 9,9-dialkylfluorene at one end is described.

Full text of DOI:10.1016/j.tetlet.2008.05.107

Tetrahedron Letters 49 (2008) 4792–4795
Contents lists available at ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Synthesis and characterization of 9,9-dialkylfluorene capped
benzo[c]thiophene/benzo[c]selenophene analogs as potential OLEDs
*
Arasambattu K. Mohanakrishnan , Natarajan Senthil Kumar, P. Amaladass
Department of Organic Chemistry, University of Madras, Guindy Campus, Chennai 600 025, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 18 March 2008
Revised 8 May 2008
Accepted 14 May 2008
Available online 28 May 2008
The synthesis of soluble benzo[c]thiophene analogs capped with 9,9-dialkylfluorene at one end is
described.
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords:
Friedel–Crafts reaction
9,9-Dialkylfluorene
Thionation/selenation
Benzo[c]thiophene/benzo[c]selenophene
Electronic properties of linear conjugated oligomers have
acquired growing importance in many areas of modern chemistry.
there are no reports on benzo[c]thiophene derivatives capped
with fluorene. In continuation of our work on benzo[c]thiophenes,8
In particular,
p-conjugated thiophene oligomers possess interest-
ing electronic and optical properties and they have been investi-
gated as Organic Field Effect Transistors (OFETs)1 and Organic
Light-Emitting Diodes (OLEDs).2 Dialkyl/diarylfluorene-containing
thienyl oligomers are reported widely in the literature. Bao and
co-workers reported the synthesis of fluorene-end capped oligo-
thiophenes which are used as organic thin film transistors.3 The
oligo(fluorenebithiophene)core was found to have high charge
transport mobility and good device performance. Lee et al.
reported the synthesis of oligo(9,9-dihexyl-2,7-fluorene ethynyl-
ene)s as a blue light-emitting diode4 whilst Pei and co-workers
have reported the synthesis of oligothiophene-truxene conju-
gates.5 Wong and co-workers reported the synthesis and photo-
physical studies of 9,9-ditolylfluorene analogs containing
thiophene rings.6
O
O
NaBH4
EtOH/THF
3
O
CO2H
reflux, 10 h
AlCl3/DCM
4 h, rt
O
R1
R1
R1
R1
2a/b
4a R1
=
=
n-C2H5 (75%)
-C6H13 (71%)
4b R1
n
i)
ii) H3O+
S
MgBr
S
O
O
O
Numerous examples of benzo[c]thiophene 1 (Fig. 1) and its
analogs7 are known in the literature. However, to our knowledge,
R1
R1
R1
R1
5a R1
5b R1
6a/b
=
=
n
n
-C2H5 (57%)
-C6H13 (60%)
i) Ar1MgBr/THF
ii) NH4Cl
Ar1
Ar2
S
Ar1
S
5a/5b
1 Ar1 = Ar2 = aryl/heteroaryl
iii) Lawesson's
reagent (0.5 eq.)
45-62%
R1
Figure 1.
R1
7a-p
* Corresponding author. Tel.: +91 44 24451108; fax: +91 44 22352494.
E-mail address: mohan_67@hotmail.com (A. K. Mohanakrishnan).
Scheme 1.
0040-4039/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2008.05.107

A. K. Mohanakrishnan et al. / Tetrahedron Letters 49 (2008) 4792–4795
4793
we report here our preliminary results on the synthesis and char-
acterization of 9,9-dialkylfluorene capped benzo[c]thiophenes/
benzo[c]selenophenes.
workup and column chromatographic purification gave the respec-
tive benzo[c]furans 6a/6b as orange-yellow solids. The 1H NMR
spectral analysis of bright yellow fluorescent solutions of 6a/6b
confirmed that these compounds were highly unstable as the solu-
tions turned red. However, ring-opening of the lactones 5a/b with
aryl/hetero-aryl Grignards10 followed by quenching with aq NH4Cl
led to the respective keto-alcohols. The DCM solution of keto-alco-
hol on thionation using 0.5 equiv of Lawesson’s reagent followed
by in situ intramolecular cyclization and subsequent column chro-
matographic purification afforded respective benzo[c]thiophene
Friedel–Crafts phthaloylation of 9,9-dialkylfluorenes 2a–b9 in
the presence of anhydrous AlCl3 in DCM at room temperature for
4 h followed by workup led to the isolation of fluorenyl keto-acids
4a–b in good yields. Reduction of the ketone carbonyl of 4a–b
using NaBH4 in EtOH/THF at reflux followed by acidic workup fur-
nished the lactones 5a/5b. Ring-opening of the lactones 5a/b using
freshly prepared 2-thienylmagnesium bromide followed by acidic
Table 1
Synthesis of benzo[c]thiophene analogs containing 9,9-dialkylfluorenes
Entry
Lactone
Ar1MgBr10
Product11
Yield (%)a mp
R1
57 (56 °C)
45 (Orange liquid)
57 (Orange liquid)
n-C2H5
n-C2H5
R1
MgBr
S
1
5a
S
R2
7a R1 = H, R2 = H
R2
S
7b R1 = H, R2
= n-C6H13
7c R1
=
n
-C6H13, R2 = H
R1
n-C2H5
n-C2H5
MgBr
R1
S
2
5a
50 (55 °C)
56 (52 °C)
52 (55 °C)
47 (59 °C)
R2
7d R1 = H, R2 = H
7e R1 = Me, R2 = H
7f R1 = H, R2 = Me
7g R1 = H, R2 = OMe
R2
MgBr
n-C2H5
n-C2H5
3
5a
52 (Yellow liquid)
S
7h
R1
n-C6H13
n
-C6H13
R1
MgBr
S
4
5b
62 (Orange liquid)
57 (Orange liquid)
50 (Orange liquid)
S
R2
7i R1 = H, R2 = H
R2
S
7j R1
= n
-C6H13, R2 = H
7k R1 = H, R2
= n-C6H13
R1
n-C6H13
n-C6H13
MgBr
R1
S
5
5b
57 (Yellow liquid)
52 (Yellow liquid)
57 (Yellow liquid)
58 (Yellow liquid)
R2
7l R1 = H, R2 = H
R2
7m R1 = Me, R2 = H
7n R1 = H, R2 = Me
7o R1 = H, R2 = OMe
MgBr
n-C6H13
n-C6H13
6
5b
55 (Yellow liquid)
S
7p
a
Isolated yield after column chromatography.

4794
A. K. Mohanakrishnan et al. / Tetrahedron Letters 49 (2008) 4792–4795
analogs 7a–p11 as highly stable compounds in 45–62% yields
(Scheme 1). The results are presented in Table 1.
Ring-opening of lactone 5a with thienyl-2-magnesium bromide
followed by thionation afforded 1-(9,9-diethylfluorenyl)-3-
thienylbenzo[c]thiophene 7a in 57% yield as an orange solid
(Table 1, entry 1). Reaction of lactone 5a with 5-hexyl-2-thienyl-
magnesium bromide/3-hexyl-2-thienylmagnesium bromide gave
benzo[c]thiophenes 7b and 7c as orange liquids in 45% and 57%
yields, respectively (Table 1, entry 1). Lactone 5a also underwent
similar reaction with aryl Grignards to afford the respective
benzo[c]thiophenes 7d-h in 47-56% yields (Table 1, entries 2 and
3). Similarly, reaction of 9,9-dihexylfluorenyl lactone 5b with thie-
nyl Grignards followed by thionation and column chromatographic
purification led to the isolation of the corresponding benzo[c]thio-
phenes 7i–k as orange liquids in 50–62% yields (Table 1, entry 4).
Similarly, reaction of lactone 5b with various aryl Grignards also
afforded the expected benzo[c]thiophenes 7l–p as yellow liquids
in 52–58% yields (Table 1, entries 5 and 6).
DMF/POCl3
rt, 10 h
S
7a/7i
S
O
R1
R1
H
10a R1
=
=
n-C2H5 (57%)
-C6H13 (61%)
10b R1
n
CH2CN
S
S
CN
S
/ EtOH
-BuOK
t
R1
R1
H
S
11a R1
=
=
n
n
-C2H5 (45%)
-C6H13 (47%)
11b R1
Scheme 4.
As a representative case, the ring-opening of the lactone 5b
with various 2-thienylmagnesium bromides followed by acidic
workup and subsequent treatment with 0.25 equiv of Woollins
reagent adopting our published procedure12 afforded benzo[c]sel-
enophene derivatives 8a–c13 in 55–62% yields, (Scheme 2). Most
of the benzo[c]thiophenes 7a–p and benzo[c]selenophenes 8a–c
were found to be highly soluble in common organic solvents.
The 9,9-dialkylfluorenyl benzo[c]thiophenes 7a/7i could be con-
verted into the corresponding dimers 9a/9b14 in low yields using
anhydrous FeCl3 in DCM (Scheme 3).
Finally, Vilsmeier–Haack formylation of 7a/7i followed by col-
umn chromatographic purification afforded aldehydes 10a/b15 in
57% and 61% yields, respectively. Condensation of these aldehydes
with thiophene-2-acetonitrile afforded the corresponding conju-
gated cyano-vinylenes 11a/b15 (Scheme 4).
compounds were recorded in DCM solution and the emission val-
ues of selected benzo[c]thiophene/benzo[c]selenophene analogs
are also presented. The HOMO and LUMO energy levels of the
benzo[c]thiophene/benzo[c]selenophene analogs were calculated
from the absorption onset and the onset oxidation potential. The
Eg, HOMO and LUMO values obtained for selected benzo[c]hetero-
cycles are presented in Table 2. The monomeric benzo[c]thio-
phene/benzo[c]selenophene analogs showed Eg values in the
range of 2.5–2.7 eV. The dimerization of benzo[c]thiophenes (7a/
i) as well as the introduction of electron-withdrawing group
(10a/b) significantly reduced the Eg values. In general, dimerization
(9a/b) reduced the HOMO energy levels (ꢀ5.3 eV to ꢀ5.1 eV) and
simultaneously enhanced the LUMO energy levels (ꢀ2.6 eV to
ꢀ2.9 eV). The introduction of an electron withdrawing group
(10a/b) significantly enhanced the LUMO energy levels (ꢀ0.3 eV).
In summary, the synthesis of various benzo[c]thiophene
analogs incorporating 9,9-dialkylfluorenyl units was achieved in
reasonable yields. The highly soluble nature of these annelated
thiophenes may make them suitable for transistor applications
through spin-coating techniques. The higher-lying HOMO energy
levels of these fluorene-incorporated benzo[c]heterocycles
(ꢀ5.2 eV) greatly reduce the energy barrier for hole injection from
ITO (u = 4.8 eV) to emissive Alq3 (u = 4.8 eV), hence, these hetero-
cycles should be explored as hole-transporting materials for
double-layer OLEDs.
The UV–vis spectra of benzo[c]thiophene/benzo[c]selenophene
analogs exhibited a strong absorption in the region of 425–
465 nm due to the
p–
p* electronic transition of the conjugated
backbone system. The exact kmax values of these compounds are
given in Table 2. The qualitative emission data of selected
R1
/Mg, THF
Br
R1
i)
R2
S
Se
5b
S
ii) HCl
R2
iii) Woollins reagent
(0.25 eq.)
n
-C6H13
-C6H13
n
8a R1 = H, R2 = H (59%)
8b R1 = -C6H13, R2 = H (62%)
8c R1 = H, R2 =
-C6H13 (55%)
n
Table 2
n
Summary of the physical properties of selected benzo[c]thiophenes/
benzo[c]selenophenes
Scheme 2.
onset
E
ox
(eV)
Compound
kmax
konset
(nm)
kemiss
(nm)
Eg
HOMOd
(eV)
LUMOe
(eV)
a
b
c
(nm)
(eV)
7i
7j
445
425
430
465
440
435
495
480
510
500
475
450
455
490
470
465
550
540
570
555
539
512
515
553
541
545
597
592
605
600
2.61
2.75
2.72
2.53
2.64
2.66
2.25
2.30
2.17
2.23
0.82
0.91
0.85
0.72
0.76
0.77
0.67
0.71
0.69
0.72
5.26
5.35
5.29
5.16
5.20
5.21
5.11
5.15
5.13
5.16
2.65
2.60
2.57
2.63
2.56
2.55
2.86
2.85
2.96
2.93
S
S
7k
8a
8b
8c
9a
9b
10a
10b
S
i) FeCl3/DCM
S
7a/7i
ii) NH2NH2.H2O
R1
R1
R1
R1
a
Measured in dilute dichloromethane solution.
Excited at the absorption maxima.
Estimated from the onset of absorption (Eg = 1240/konset).
9a R1
9b R1
=
=
n
n
-C2H5 (45%)
-C6H13 (40%)
b
c
d
e
onset
ox
Calculated using the empirical equation: HOMO ¼ ð4:44 þ E
Þ.
Calculated from LUMO = HOMO ꢁ Eg.
Scheme 3.

A. K. Mohanakrishnan et al. / Tetrahedron Letters 49 (2008) 4792–4795
4795
1H), 7.35–7.38 (m, 4H), 7.57–7.60 (m, 1H), 7.64–7.68 (m, 2H), 7.73–7.74 (m,
1H), 7.82–7.85 (m, 1H). 13C NMR (75 MHz, CDCl3): d 8.6, 14.1, 22.6, 29, 29.1,
30.8, 31.6, 32.8, 56.3, 119.8, 120.2, 121.0, 121.8, 123.0, 123.7, 124.0, 124.2,
125.9, 127.0, 127.3, 128.1, 128.2, 129.3, 132.8, 134.3, 136.2, 138.0, 139.2, 141,
141.1, 142.3, 150.2, and 150.8. Anal. Calcd for C35H36S2: C, 80.72; H, 6.97; S,
12.31. Found: C, 80.84; H, 7.05; S, 12.11.
Acknowledgements
We thank DST, New Delhi (SR/S1/OC-37/2005) and UGC-Poten-
tial for excellence for financial support. N.S. thanks DST for a
fellowship. Financial support from the Department by DST-FIST is
also acknowledged.
Compound 7i: viscous orange liquid; 1H NMR (300 MHz, CDCl3): d 0.79–0.89
(m, 10H), 10.8–1.24 (m, 12H), 2.10–2.18 (m, 4H), 7.10–7.22 (m, 3H), 7.36–7.47
(m, 4H), 7.61–7.62 (m, 1H), 7.80–7.88 (m, 3H), 7.92–8.02 (m, 3H). 13C NMR
(75 MHz, CDCl3): d 14.1, 22.7, 23.9, 29.8, 31.6, 40.5, 55.3, 119, 119.8, 120.1,
120.3, 120.4, 121.9, 122.2, 122.9, 123.9, 124.0, 125.3, 125.4, 125.5, 127.0, 127.2,
127.9, 130.3, 133.8, 140.1, 140.3, 140.8, 144.3, 151.1, and 151.6. Anal. Calcd for
References and notes
1. (a) Bao, Z.; Dodabalapur, A.; Lovinger, A. J. Appl. Phys. Lett. 1996, 69, 4108–4110;
(b) Sirringhaus, H.; Tessler, N.; Friend, R. H. Science 1998, 280, 1741–1744; (c)
Li, X. C.; Sirringhaus, H.; Garnier, F.; Holmes, A. B.; Moratti, S. C.; Feeder, N.;
Clegg, W.; Teat, S. J.; Friend, R. H. J. Am. Chem. Soc. 1998, 120, 2206–2207.
2. (a) Burroughes, J. H.; Bradley, D. D. C.; Brown, A. R.; Marks, R. N.; Mackay, K.;
Friend, R. H.; Burn, P. L.; Holmes, A. B. Nature 1990, 347, 539–541; (b) Noda, T.;
Ogawa, H.; Noma, N.; Shirota, Y. J. Chem. Mater. 1999, 9, 2177–2181.
3. Meng, H.; Zheng, J.; Lovinger, A. J.; Wang, B.-C.; Patten, P. G. V.; Bao, Z. Chem.
Mater. 2003, 15, 1778–1787.
4. Lee, S. H.; Nakamura, T.; Tsutsui, T. Org. Lett. 2001, 3, 2005–2007.
5. (a) Pei, J.; Ni, J.; Zhou, X.-H.; Cao, X.-Y.; Lai, Y.-H. J. Org. Chem. 2002, 67, 4924–
4936; (b) Pei, J.; Wang, J.-L.; Cao, X.-Y.; Zhou, X.-H.; Zhang, W.-B. J. Am. Chem.
Soc. 2003, 125, 9944–9945; (c) Wang, J.-L.; Luo, J.; Liu, L.-H.; Zhou, Q.-F.; Ma, Y.;
Pei, J. Org. Lett. 2006, 8, 2281–2284.
C
37H40S2: C, 80.97; H, 7.35; S, 11.68. Found: C, 80.85; H, 7.30; S, 11.85.
Compound 7o: viscous yellow liquid; 1H NMR (300 MHz, CDCl3): d 0.62–0.65
(m, 10H), 0.89–1.11 (m, 12H), 1.80–1.83 (m, 4H), 3.71 (s, 3H), 6.95–6.98 (m,
4H), 7.20–7.24 (m, 3H), 7.49–7.73 (m, 8H). 13C NMR (75 MHz, CDCl3): d 14.0,
22.6, 23.8, 29.7, 31.5, 40.5, 55.2, 55.3, 114.6, 118.8, 119.7, 119.8, 120.2, 120.3,
121.3, 122.0, 122.9, 123.6, 124.7, 124.8, 125.1, 126.3, 126.9, 127.0, 130.4, 130.6,
139.8, 140.8, 143.9, 151.0, 151.5, and 158.8. Anal. Calcd for C40H44S2: C, 83.87;
H, 7.74; S, 5.60. Found: C, 83.80; H, 7.79; S, 5.65.
12. Mohanakrishnan, A. K.; Amaladass, P. Tetrahedron Lett. 2005, 46, 7201–7204.
13. Spectral data for 8b: viscous yellow liquid; 1H NMR (300 MHz, CDCl3): d 0.81–
0.90 (m, 13H), 1.15–1.32 (m, 18H), 1.61–1.68 (m, 2H), 2.05–2.10 (m, 4H), 2.71
(t, J = 7.8 Hz, 2H), 7.00–7.04 (m, 2H), 7.12 (d, J = 5.4 Hz, 1H), 7.37–7.48 (m, 5H),
7.63–7.66 (m, 2H), 7.74–7.85 (m, 3H). 13C NMR (75 MHz, CDCl3): d 14.0, 14.1,
22.6, 23.9, 29.0, 29.1, 29.7, 30.8, 31.5, 31.6, 40.4, 55.2, 119.9, 120.2, 121.6,
122.4, 123.0, 123.7, 123. 8, 124.0, 125.9, 126.9, 127.3, 128.7, 129.2, 130.6,
132.8, 134.8, 136.6, 140.6, 140.8, 142.0, 146.1, 151.1, and 151.5. Anal. Calcd for
6. Wong, K.-T.; Hwu, T.-Y.; Balaiah, A.; Chao, T.-C.; Fang, F.-C.; Lee, C.-T.; Peng, Y.-
C. Org. Lett. 2006, 8, 1415–1418.
7. (a) Lorcy, D.; Cava, M. P. Adv. Mater. 1992, 4, 562–564; (b) Bauerle, P.; Gotz, G.;
Emerle, P.; Port, H. Adv. Mater. 1992, 4, 564–568; (c) Musinanni, S.; Ferraris, J. P.
J. Chem. Soc., Chem. Commun. 1993, 172–174; (d) Kiebooms, R. H. L.;
Adriaensens, P. J. A.; Vanderzande, D. J. N.; Gelan, J. M. J. V. J. Org. Chem.
1997, 62, 1473–1480; (e) Mohanakrishnan, A. K.; Lakshmikantham, M. V.;
McDougal, C. D.; Cava, M. P.; Baldwin, J. W.; Metzger, R. M. J. Org. Chem. 1998,
63, 3105–3112; (f) Raimundo, J. M.; Blanchard, P.; Brisset, H.; Akoudad, S.;
Roncali, J. Chem. Commun. 2000, 939–940; (g) Strassler, C.; Davis, N. E.; Kool, E.
T. Helv. Chim. Acta 1999, 82, 2160–2171; (h) Tan, S.; Bhowmik, A. K.; Thakur,
M.; Lakshmikantham, M. V.; Cava, M. P. J. Chem. Phys. 2000, 112, 383–385.
8. (a) Mohanakrishnan, A. K.; Amaladass, P. Tetrahedron Lett. 2005, 46, 4225–
4229; (b) Mohanakrishnan, A. K.; Amaladass, P.; Arul Clement, J. Tetrahedron
Lett. 2007, 48, 779–784; (c) Mohanakrishnan, A. K.; Arul Clement, J.;
Amaladass, P.; Thirunavukkarasu, V. S. Tetrahedron Lett. 2007, 48, 8715–8720.
9. The required 9,9-dialkylfluorenes 2a/2b were prepared from fluorene via
successive lithiations using n-BuLi/THF at ꢁ78 °C, followed by quenching with
alkyl halides.
C
A
43H52SSe: C, 75.96; H, 7.71; S, 4.72. Found: C, 76.10; H, 7.70; S, 4.65.
14.
representative procedure for the synthesis of 9a: solution of 7a (0.4 g,
A
0.92 mmol) in dry CH2Cl2 was treated with FeCl3 (0.30 g, 1.85 mmol) under a
2 atmosphere at room temperature for 6 h. The reaction mixture was treated
N
with a dilute solution of N2H4ꢂH2O. Evaporation of the solvent followed by
column chromatography (silica gel, hexane–EtOAc; 10:1) gave the dimer 9a
(0.18 g, 45%).
Spectral data for 9a: semi-solid; 1H NMR (300 MHz, CDCl3): d 0.35 (t, J = 7.4 Hz.
12H), 2.0 (q, J = 7.4 Hz, 8H), 6.86–6.89 (m, 4H), 7.0–7.3 (m, 14H), 7.5 (m, 2H),
7.61–7.8 (m, 4H), 7.98 (d, J = 8.7 Hz, 2H). 13C NMR (75 MHz, CDCl3): d 8.6, 32.8,
56.3, 119.9, 120.2, 121.7, 123.0, 123.7, 124.3, 124.5, 124.9, 125.8, 126.1, 126.3,
126.9, 127.0, 127.4, 128.2, 132.5, 135.2, 135.3, 135.4, 136.6, 140.9, 141.3, 150.2,
and 150.9. Anal. Calcd for C58H46S4: C, 79.96; H, 5.32; S, 14.72. Found: C, 80.05;
H, 5.35; S, 14.60.
15. Spectral data for aldehyde 10b: red liquid; 1H NMR (300 MHz, CDCl3): d 0.81–
0.95 (m, 10H), 1.15–1.31 (m, 12H), 2.17–2.22 (m, 4H), 7.29–7.37 (m, 3H), 7.41
(d, J = 3.9 Hz, 1H), 7.61–7.66 (m, 5H), 7.67–7.81 (m, 3H), 7.81 (d, J = 8.3 Hz, 1H),
9.61 (s, 1H, CHO). 13C NMR (75 MHz, CDCl3): d 14.2, 22.7, 23.1, 29.5, 31.9, 40.7,
55.1, 119.1, 120.7, 121.4, 121.5, 123.1, 123.9, 124.7, 125.1, 126.9, 127.7, 128.5,
132.1, 133.9, 135.5, 136.1, 137.7, 138.5, 140.5, 141.5, 141.7, 147.1, 150.7, and
181.7.
10. The required aryl/hetero-aryl Grignard reagents were prepared from the
corresponding bromo compounds by refluxing with magnesium in dry THF
under a N2 atmosphere.
11. Spectral data of selected benzo[c]thiophenes:Compound 7a: mp 56 °C; 1H NMR
(300 MHz, CDCl3): d 0.40 (t, J = 3.6 Hz, 6H), 2.06–2.15 (m, 4H), 7.01 (m, 1H),
7.14 (t, J = 3 Hz, 1H), 7.29–7.36 (m, 5H), 7.53 (d, J = 3 Hz, 1H), 7.7–7.92 (m, 6H).
13C NMR (75 MHz, CDCl3): d 8.6, 32.9, 56.3, 118.9, 119.7, 120.1, 120.2, 120.3,
121.8, 122.2, 122.9, 123.8, 123.9, 125.2, 125.4, 125.6, 127.1, 127.2, 127.9, 130.2,
133.7, 140.1, 140.6, 141.1, 144.2, 150.2, and 150.7. Anal. Calcd for C29H24S2: C,
79.77; H, 5.54; S, 14.69. Found: C, 79.60; H, 5.62; S, 14.78.
Spectral data for cyanovinylene 11b: black solid; mp 117 °C; 1H NMR (300 MHz,
CDCl3): d 0.78–0.84 (m, 10H), 1.18–1.20 (m, 12H), 2.01–2.12 (m, 4H), 7.1 (t,
J = 8.4 Hz, 1H), 7.13 (t, J = 8.7 Hz, 1H), 7.33–7.43 (m, 4H), 7.51–7.55 (m, 2H),
7.59–7.66 (m, 4H), 7.73–7.81 (m, 1H), 7.81–7.90 (m, 3H), 8.49–8.52 (m, 1H).
13C NMR (75 MHz, CDCl3): d 14.0, 22.6, 23.9, 29.8, 31.5, 40.5, 55.3, 119.0, 119.7,
120.2, 120.3, 120.5, 121.5, 122.9, 123.7, 124.2, 124.8, 125.3, 125.5, 125.8, 126.2,
126.3, 126.6, 126.9, 127.1, 127.4, 127.9, 128.6, 128.7, 130.6, 131.1, 134.4, 140.2,
140.8, 144.2, 145.6, 151.1, and 151.6. Anal. Calcd for C44H43NS3: C, 77.49; H,
6.35; N, 2.05; S, 14.10. Found: C, 77.35; H, 6.31; N, 2.15; S, 14.18.
Compound 7c: viscous orange liquid; 1H NMR (300 MHz, CDCl3): d 0.41 (t,
J = 7.35 Hz, 6H), 0.79–0.83 (m, 3H), 1.21–1.25 (m, 6H), 1.55-1.63 (m, 2H), 2.08
(q, J = 7.4 Hz, 4H), 2.67 (t, J = 8.25 Hz, 2H), 7.06–7.11 (m, 3H), 7.29–7.34 (m,