Studies on the preference of multiple coupling in the introduction of thiophene ring into poly-halogenated aromatic compounds with nickel NHC catalyst

Article abstract of DOI:10.1016/j.tetlet.2013.01.127

Several thiophene derivatives can be deprotonated by the combination of ethyl magnesium chloride (EtMgCl) and a catalytic amount of 2,2,6,6- tetramethylpiperidine (TMP-H). The metalated 3-hexylthiophene reacts with 2,3- and 2,5-dibromothiophenes in the presence of a nickel catalyst bearing NHC ligand (IPr) to afford the di-coupled product exclusively along with recovery of dibromothiophene albeit the equimolar reaction. The 1:1 reaction of 3-hexylthiophene with dibrominated benzene derivatives also gives di-coupled product as a sole product.

Full text of DOI:10.1016/j.tetlet.2013.01.127

Tetrahedron Letters 54 (2013) 1976–1979
Contents lists available at SciVerse ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Studies on the preference of multiple coupling in the introduction
of thiophene ring into poly-halogenated aromatic compounds
with nickel NHC catalyst
⇑
Shota Tanaka, Go Tatsuta, Atsushi Sugie, Atsunori Mori
Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Several thiophene derivatives can be deprotonated by the combination of ethyl magnesium chloride
(EtMgCl) and a catalytic amount of 2,2,6,6-tetramethylpiperidine (TMP-H). The metalated 3-hexylthioph-
ene reacts with 2,3- and 2,5-dibromothiophenes in the presence of a nickel catalyst bearing NHC ligand
(IPr) to afford the di-coupled product exclusively along with recovery of dibromothiophene albeit the
equimolar reaction. The 1:1 reaction of 3-hexylthiophene with dibrominated benzene derivatives also
gives di-coupled product as a sole product.
Received 9 January 2013
Revised 28 January 2013
Accepted 30 January 2013
Available online 8 February 2013
Keywords:
N-Heterocyclic carbenes ligand
Nickel catalyst
Ó 2013 Elsevier Ltd. All rights reserved.
Thiophene
Multiple coupling
Oligothiophene
1. Introduction
reaction with the thus obtained oligomer leads to oligothiophene
dendrimers of higher generations (Scheme 1).
Oligothiophene derivatives have attracted much interest as
p
-
During the course of our further studies on oligothiophene den-
drimers we have learned that the reaction of 2,3-dibromothio-
phene (1a) with 2.5 equiv of 3-hexylthiophene (2a) proceeds
rapidly to give branched oligothiophene 3-mer 3aa in a quantita-
tive yield after stirring at room temperature for several hours in
the presence of 2.0 mol % of a nickel catalyst bearing a N-heterocy-
clic carbenes (NHC) ligand, NiCl2(PPh3)IPr,10,11 while no mono-cou-
pled byproduct 4aa was observed. Even in the 1:1 reaction of 1a, 2,
and 3aa was the sole product along with recovery of unreacted 2,3-
dibromothiophene (Scheme 2).
conjugated materials for organic electronic devices.1 Development
of synthetic method of oligothiophenes is a significant issue in or-
ganic chemistry, accordingly. In oligothiophene synthesis, cross-
coupling reaction of thiophene–metal species with halothiophene
has generally been employed to form thiophene–thiophene bond.2
In addition, coupling reactions at the C–H bond of thiophene have
been recently reported3 and applied to the synthesis of organic
functional materials bearing thiophene unit.4 Development of C–
H
coupling of heteroaromatic compounds with aryl halide
has therefore been our major concern5 and we have recently
reported oligothiophene6 and polythiophene7 synthesis with
deprotonative metalation of thiophene with Knochel–Hauser base
(TMPMgClꢀLiCl)8 or the combination of Grignard reagent and a cat-
alytic amount of secondary amine and the following nickel-cata-
lyzed cross-coupling reaction with a halide of thiophene. We
have also shown that oligothiophene dendrimers are synthesized
in a facile manner when regioselective metalation of 3-substituted
thiophene and the following coupling of 2,3-dibromothiophene in
the presence of a nickel catalyst are employed.9 The reaction af-
fords branched oligothiophene 3-mer and repeating the similar
Related unexpected reactivity enhancement in the second cross-
coupling reaction was recently shown by Larrosa et al., with several
polyhalogenated aromatic compounds and several organometallic
compounds in the presence of palladium catalyst, PEPPSI.12,13 It
has also been shown by Yokozawa that several cross-coupling poly-
condensations take place in a catalyst transfer manner to undergo
intramolecular migration of a transition-metal catalyst, in which
chain-growth polymerization proceeds despite polycondensa-
tion,14,15 the reaction of which would also be the related enhanced
reactivity. However, there are a few systematic studies on such en-
hanced multiple coupling related with requirements of substrate
and reagent structures as well as ligand and metal species of the cat-
alyst. Herein, we report studies on the preference of an enhanced
multiple coupling of metalated thiophenes in the presence of a tran-
sition-metal-catalyst with poly-halogenated organic electrophiles.
⇑
Corresponding author. Tel./fax: +81 78 803 6181.
E-mail address: amori@kobe-u.ac.jp (A. Mori).
0040-4039/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2013.01.127

S. Tanaka et al. / Tetrahedron Letters 54 (2013) 1976–1979
1977
nHex
Table 1
Br
Br
The reaction of 2,3-dibromothiophene (1a) with 1.2 equiv of several thiophene
derivativesa
TMP-H
nHex
nHex
S
S
S
(10 mol%)
EtMgCl
1a
ClMg
2-MgCl
H
2
1) metalation of
NiCl2(PPh3)IPr
(2.0 mol%)
S
THF, reflux
24 h
S
S
with EtMgCl and
TMP-H (10 mol%)
THF, reflux
Br
2a
S
nHex
Br
Br
3aa
>99%
room temp
nHe xn
S
S
+
Hex
S
nHex
S
+
H
2) NiCl2(PPh3)IPr
nHex
S
S
S
S
S
S
(2.0 mol%)
S
S
S
4
S
THF, 60 °C, 24 h
3
1a
0.5 mmol
2
nHe x
nHex
nHex
nHex
S
S
1.2 eq.
S
S
S
S
S
S
S
S
Entry
2
Yieldb (%)
S
S
15T
)
7T
(
(
)
nHex
nHex
nHex
S
S
3
4
nHex
Scheme 1. Stepwise synthesis of oligothiophene dendrimers by regioselective
coupling.
1
2
34 (3ab)
51 (3ac)
3c (4ab)
Me 2b
Me
S
S
0
2c
nC8H17
nHex
1) metalation of 2a
with EtMgCl and
nHex
3
4
56 (3ad)
33 (3ae)
0
0
Br
Br
TMP-H (10 mol%)
2) catalyst
(2.0 mol%)
Br
S
S
S
2d
nC12H25
S
H
S
+
+
S
1a
S
S
S
2a
nHex
nHex
2e
1.0 eq.
3aa
4aa
41%
33%
17%
0%
0%
NiCl2(PPh3)IPr
NiCl2(dppe)
Pd-PEPPSI-IPr
5
6
49 (3af)
49 (3ag)
22 (3ah)
0
0
0
S
S
2f
32%
2g
Scheme 2. The 1:1 reaction of 1a and 2a with several nickel or palladium catalysts.
7
O
2h
2. Results and discussion
a
Unless otherwise noted, the reaction was carried out with 2 (0.6 mmol), 1a
(0.5 mmol), and NiCl2(PPh3)IPr (0.01 mmol) in 2.0 mL of THF at 60 °C for 24 h.
We first examined the reaction of 2,3-dibromothiophene (1a)
with a variety of thiophene derivatives 2b–g (1.2 equiv) in the
presence of 2.0 mol % of NiCl2(PPh3)IPr. Results are summarized
in Table 1. In addition to 3-hexylthiophene, the reaction of 2-meth-
ylthiophene (2b) also took place to afford di-coupled product 3ab
in 34% yield along with 3% of the mono-coupled product 4ab (entry
1). The reaction of 3-methylthiophene (3c) gave 3ac exclusively in
51% yield. Other 3-alkylated thiophenes, 3-octylthiophene (2d),
and 3-dodecylthiophene (2e), also reacted with 1a to afford the
di-coupled product (entries 3 and 4). The reaction of benzo[b]thio-
phene (2f) occurred to give 3af exclusively in 49% yield (entry 5).
Unsubstituted thiophene reacted with 1a to afford 3ag in 49% yield
(entry 6). In addition to thiophene derivatives, the reaction of ben-
zo[b]furan (2h) was found to react with 1a to afford 3ah in 22%
yield, while no mono coupling product was obtained (entry 7).
We next investigated the 1.0–1.2 equiv reaction of 3-hexylthi-
ophene (2a) with a variety of poly-halogenated arenes in the pres-
ence of 2.0 mol % of NiCl2(PPh3)IPr. Table 2 summarizes the results.
The reaction of 2a with 2,5-dibromothiophene (1b) proceeded
smoothly to give terthiophene 3ba exclusively in 36% yield. In
addition to dibromothiophenes, a similar effect was observed in
the reaction of several bromobenzenes. When 1,4-dibromoben-
zene (1d) was used as a coupling partner, the reaction took place
to give di-coupled product 3ca in 45% yield selectively. The similar
trend was also observed in the reaction of 1,3-dibromobenzene
(1d) and 1,2-dibromobenzene (1e) to afford 3da and 3ea in 44%
and 44% yield, respectively. The reaction of 1,2-chlorobenzene
(1f) also furnished di-coupled product 3ea in 36% yield. When
dibrominated bithiophene with dimethylsilylene spacer 1g was
employed, the reaction proceeded to afford the mixture of di-cou-
pled product 3ga and mono-coupled product 4ga in 27% and 17%
yields, respectively.
b
Isolated yield. The yield was calculated on the basis of amount of 1a.
The yield was determined by GC analysis.
c
Results obtained in Tables 1 and 2 show that multiple coupling
of thiophene derivatives with halides of thiophene and benzene
ring successfully takes place catalyzed by a nickel complex bearing
a NHC ligand despite the use of ca. 1:1 metalated thiophene and
multiply halogenated substrate. Although details on the preference
of multiple coupling have not been clear yet, slower reductive
elimination of thiophene–Ni–thiophene due to the electron-donat-
ing effect of NHC as well as higher reduction potential of nickel(II)
may facilitate intramolecular migration to the second carbon–bro-
mine bond. On the other hand, the reaction with palladium catalyst
such as PEPPSI–IPr resulted in giving the mono-coupling product
predominantly in the case of thiophene–thiophene coupling
(Scheme 2).9 The remarkable effect of Ni NHC complex as a catalyst
seems to be a specific case in the thiophene coupling compared
with the related 1:1 reactions of other metallo arenes and alkanes,
in which the use of PEPPSI–IPr has effectively undergone multiple
coupling.12 Although we have also examined the multiple coupling
reaction of 2,3-dibromothiophene with Grignard reagent PhMgBr
in the presence of NiCl2(PPh3)IPr, mono-coupling product was ob-
tained as a major product.16 These results suggest that preference
of the enhanced multiple coupling occurs only when conditions of
substrates and the catalyst show a good match whereas a mis-
matched reaction prefers mono-coupling.
The accelerated multiple coupling is suggested to occur in the
case of substrates bearing a p-conjugated system. Indeed, the reac-
tion of metalated 1a with 1g bearing a dimethylsilylene spacer be-
tween bromothiophenes resulted that preferential dicoupling was
not observed to afford a mixture of mono- and dicoupled products.

1978
Table 2
S. Tanaka et al. / Tetrahedron Letters 54 (2013) 1976–1979
and substrate. This reaction was also shown to be effective for a
wide range of poly-halogenated arenes such as 1,4-and 1,2-
dihalobenzene.17
The reaction of 1.0–1.2 equiv of 3-hexylthiophene (2a) with poly-halothiophene
derivativesa
nHex
S
2a
1) metalation of
Aryl
nHex
with EtMgCl and
TMP-H (10 mol%)
THF, reflux
Acknowledgments
S
nHex
3
X
Aryl
X
+
H
+
This work was partially supported by Kakenhi (B22350042) by
JSPS and Nagase Science Promotion Foundation. S.T. thanks Sasag-
awa Scientific Research Grant by The Japan Science Society for
financial support.
nHex
S
2a
2) NiCl2(PPh3)IPr
(X = Br, Cl)
1
0.5 mmol
(2.0 mol%)
Aryl
X
THF, 60 °C, 24 h
S
1.0-1.2 eq.
4
Entry
1
Yieldb (%)
References and notes
3
4
1. For reviews: (a) Mishra, A.; Bäuerle, P. Angew. Chem., Int. Ed. 2012, 51, 2020; (b)
Murphy, A. R.; Frèchet, J. M. J. Chem. Rev. 2007, 107, 1066; (c) Facchetti, A.;
Yoon, M.-H.; Marks, T. J. Adv. Mater. 2005, 17, 1705; (d) Allard, S.; Forster, M.;
Souharce, B.; Thiem, H.; Scherf, U. Angew. Chem., Int. Ed. 2008, 47, 4070.
2. Mishra, A.; Ma, C.-Q.; Bäuerle, P. Chem. Rev. 2009, 109, 1141.
1c
2c
36 (3ba)
0
0
Br 1b
Br
Br
S
45d (3ca)
44 (3da)
Br 1c
3. For reviews: (a) Ackermann, L.; Vicente, R.; Kapdi, A. R. Angew. Chem., Int. Ed.
2009, 48, 9792; (b) Cho, S. H.; Kim, J. Y.; Kwak, J.; Chang, S. Chem. Soc. Rev. 2011,
40, 5068; (c) Daugulis, O.; Do, H.-Q.; Shabashov, D. Acc. Chem. Res. 2009, 42,
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M. E.; Lautens, M. Chem. Rev. 2007, 107, 174; (f) Lapointe, D.; Fagnou, K. Chem.
Lett. 2010, 39, 1118; (g) Seregin, I. V.; Gevorgyan, V. Chem. Soc. Rev. 2007, 36,
1173; (h) McGlacken, G. P.; Bateman, L. M. Chem. Soc. Rev. 2009, 38, 2447.
4. (a) Facchetti, A.; Vaccaro, L.; Marrocchi, A. Angew. Chem., Int. Ed. 2012, 51, 3520;
(b) Fujinami, Y.; Kuwabara, J.; Lu, W.; Hayashi, H.; Kanbara, T. ACS Macro Lett.
2012, 1, 67; (c) Wang, Q.; Takita, R.; Kikuzaki, Y.; Ozawa, F. J. Am. Chem. Soc.
2010, 132, 11420; (d) Kamiya, H.; Yanagisawa, S.; Hiroto, S.; Itami, K.;
Shinokubo, H. Org. Lett. 2011, 13, 6394; (e) Schipper, D. J.; Fagnou, K. Chem.
Mater. 2011, 23, 1594.
5. (a) Sugie, A.; Mori, A. Bull. Chem. Soc. Jpn. 2008, 81, 548; (b) Mori, A. J. Synth. Org.
Chem. Jpn. 2011, 69, 1202; (c) Mitsuda, S.; Fujiwara, T.; Kimigafukuro, K.;
Monguchi, D.; Mori, A. Tetrahedron 2012, 68, 3585; (d) Mori, A.; Sekiguchi, A.;
Masui, K.; Shimada, T.; Horie, M.; Osakada, K.; Kawamoto, M.; Ikeda, T. J. Am.
Chem. Soc. 2003, 125, 1700; (e) Masui, K.; Ikegami, H.; Mori, A. J. Am. Chem. Soc.
2004, 126, 5074; (f) Takahashi, M.; Masui, K.; Sekiguchi, H.; Kobayashi, N.;
Mori, A.; Funahashi, M.; Tamaoki, N. J. Am. Chem. Soc. 2006, 128, 10930; (g)
Monguchi, D.; Fujiwara, T.; Furukawa, H.; Mori, A. Org. Lett. 2009, 11, 1607.
6. Tanaka, S.; Tamba, S.; Tanaka, D.; Sugie, A.; Mori, A. J. Am. Chem. Soc. 2011, 133,
16734.
Br
3c
4
0
0
0
Br
1d
Br
Cl
Br
44 (3ea)
1e
Cl
5c
36 (3ea)
27 (3ga)
1f
6e
17 (4ga)
Br
Si
Br
S
S
1g
a
Unless noted, the reaction was performed with 2a (0.6 mmol), haloarene
(0.5 mmol), and NiCl2(PPh3)IPr (0.01 mmol) in 2.0 mL of THF.
b
Isolated yield. The yield was calculated on the basis of amount of 1a.
c
The reaction was carried out with 2a (0.5 mmol).
The yield was estimated by 1H NMR analysis.
d
e
The reaction was carried out with 0.254 mmol of 1g.
7. (a) Tamba, S.; Shono, K.; Sugie, A.; Mori, A. J. Am. Chem. Soc. 2011, 133, 9700; (b)
Tamba, S.; Tanaka, S.; Okubo, Y.; Okamoto, S.; Meguro, H.; Mori, A. Chem. Lett.
2011, 40, 398.
8. (a) Haag, B.; Mosrin, M.; Ila, H.; Malakhov, V.; Knochel, P. Angew. Chem., Int. Ed.
2011, 50, 9794; (b) Krasovskiy, A.; Krasovskaya, V.; Knochel, P. Angew. Chem.,
Int. Ed. 2006, 45, 2958; (c) Hauser, C. R.; Frostick, F. C. J. Am. Chem. Soc. 1949, 71,
1350.
9. Tanaka, S.; Tanaka, D.; Tatsuta, G.; Murakami, K.; Tamba, S.; Sugie, A.; Mori, A.
Chem. Eur. J. 2013, 19, 1658.
10. Matsubara, K.; Ueno, K.; Shibata, Y. Organometallics 2006, 25, 3422.
11. Reviews on transition metal catalyst with NHC ligand, see: (a) Herrmann, W. A.
Angew. Chem., Int. Ed. 2002, 41, 1290; (b) Diez-Gonzalez, S.; Marion, N.; Nolan,
S. P. Chem. Rev. 2009, 109, 3612; (c) Kantchev, E. A. B.; O’Brien, C. J.; Organ, M.
G. Angew. Chem., Int. Ed. 2007, 46, 2768.
12. Larrosa, I.; Somoza, C.; Banquy, A.; Goldup, S. M. Org. Lett. 2011, 13, 146.
13. PEPPSI: Pyridine-enhanced precatalyst preparation stabilization and initiation.
See: (a) O’Brien, C. J.; Kantchev, E. A. B.; Valente, C.; Hadei, N.; Chass, G. A.;
Lough, A.; Hopkinson, A. C.; Organ, M. G. Chem. Eur. J. 2006, 12, 4743; (b) Organ,
M. G.; Calimsiz, S.; Sayah, M.; Hoi, K. H.; Lough, A. J. Angew. Chem., Int. Ed. 2009,
48, 2383.
14. (a) Yokozawa, T.; Yokoyama, A. Chem. Rev. 2009, 109, 5595; (b) Yokoyama, A.;
Yokozawa, T. Macromolecules 2007, 40, 4093; (c) Yokozawa, T.; Nanashima, Y.;
Ohta, Y. ACS Macro Lett. 2012, 1, 862; (d) Miyakoshi, R.; Yokoyama, A.;
Yokozawa, T. J. Am. Chem. Soc. 2005, 127, 17542; (e) Yokoyama, A.; Suzuki, H.;
Kubaota, Y.; Ohuchi, K.; Higashimura, H.; Yokozawa, T. J. Am. Chem. Soc. 2007,
129, 7236; (f) Miyakoshi, R.; Shimono, K.; Yokoyama, A.; Yokozawa, T. J. Am.
Chem. Soc. 2006, 128, 16012; (g) Nojima, M.; Ohta, Y.; Yokozawa, T. Polym. Prep.
Jpn. 2012, 60, 2728; (h) Nanashima, Y.; Yokoyama, A. Yokozawa
Macromolecules 2012, 45, 2609.
15. See also: (a) Sheina, E. E.; Liu, J. S.; Iovu, M. C.; Laird, D. W.; McCullough, R. D.
Macromolecules 2004, 37, 3526; (b) Iovu, M. C.; Sheina, E. E.; Gil, R. R.;
McCullough, R. D. Macromolecules 2005, 38, 8649; (c) Tkachov, R.; Senkovskyy,
V.; Komber, H.; Sommer, J.-U.; Kiriy, A. J. Am. Chem. Soc. 2010, 132, 7803; (d)
Beryozkina, T.; Boyko, K.; Khanduyeva, N.; Senkovskyy, V.; Horecha, M.; Oertel,
U.; Simon, F.; Stamm, M.; Kiriy, A. Angew. Chem., Int. Ed. 2009, 48, 2695; (e)
Tkachov, R.; Senkovskyy, V.; Komber, H.; Kiriy, A. Macromolecules 2011, 44,
2006; (f) Huang, W.; Su, L.; Bo, Z. J. Am. Chem. Soc. 2009, 131, 10348.
16. On the other hand, McCullough et al. have reported successive coupling of 2,5-
dibromothiophene with tolyl magnesium bromide was took place in the
presence of NiCl2(dppp) in Ref. 15a.
nHex
nHex
Ni
Br
Ni
Br
S
reductive
S
elimination
nHex
BrNi
oxidative
addition
S
Scheme 3. Catalyst transfer through reductive elimination and oxidative addition
sequence
The result would closely relate with the catalyst-transfer mecha-
nism in the chain-growth cross-coupling polycondensation of
thiophenes proposed by Yokozawa,14,15 in which there is intra-
moleculer transfer of Ni species through the p-conjugated system
by reductive elimination and oxidative addition sequence
(Scheme 3). It is remarkable that such catalyst-transfer effect
would also facilitate the coupling reaction at the second carbon–
bromine bond in the
oligothiophenes.
p-conjugated system leading to branched
3. Conclusion
In conclusion, we have shown that successive multiple coupling
reaction of thiophene derivatives with dibrominated thiophene in
the presence of nickel NHC catalyst NiCl2(PPh3)IPr proceed to give
di-coupled product, exclusively despite the use of ca. 1:1 reagent

S. Tanaka et al. / Tetrahedron Letters 54 (2013) 1976–1979
1979
17. Representative procedure: To a 20 mL Schlenk tube equipped with a magnetic
stirring bar were added 0.99 M EtMgCl (0.505 mL, 0.5 mmol) in THF and TMP-
H (0.008 mL, 0.05 mmol). To the solution were added 3-hexylthiophene (2a,
0.09 mL, 0.50 mmol) and stirring was continued under reflux for 24 h. Then,
1.4 mL of THF, 1,3-dibromobenzene (1d, 118 mg, 0.5 mmol) and NiCl2(PPh3)IPr
(7.8 mg, 0.01 mmol) were added successively. The mixture was allowed to stir
at 60 °C for 24 h. The mixture was quenched by saturated aqueous solution of
ammonium chloride (1.0 mL). The solution was poured into the mixture of
diethyl ether/water and two phases were separated. Aqueous was extracted
with diethyl ether twice and the combined organic layer was dried over
anhydrous sodium sulfate and concentrated under reduced pressure to leave a
crude oil, which was purified by column chromatography on silica gel using
hexanes as an eluent to afford 89.7 mg 1,3-bis(3-hexylthiophen-5-yl)benzene
(3da, 44%, pale yellow oil). 1H NMR (CDCl3, 300 MHz) d 0.90 (t, J = 6.8 Hz, 6H),
1.18–1.48 (m, 12H), 1.59–1.75 (m, 4H), 2.63 (t, J = 7.7 Hz, 4H), 6.89 (d,
J = 0.9 Hz, 2H), 7.20 (d, J = 1.3 Hz, 2H), 7.31–7.39 (m, 1H), 7.48 (dd, J = 1.7,
7.0 Hz, 2H), 7.79 (t, J = 1.7 Hz, 1H); 13C NMR (CDCl3, 75 MHz) d 14.1, 22.6, 29.0,
30.4, 30.6, 31.7, 119.7, 123.1, 124.7, 124.8, 129.3, 135.3, 143.6, 144.3; IR (ATR)
2954, 2926, 2854, 1600, 1577, 1559, 1549, 1489, 1465, 1458, 1377, 1261, 1204,
1088, 1025, 880, 837, 787, 729, 687, 668, 652, 633 cmꢁ1; HRMS (DART-ESI+)
Calcd for C26H35S2 [M+H]+:411.2180; Found: m/z 411.2164.
30.5, 31.9, 119.9, 121.2, 124.0, 127.8, 129.2, 129.7, 131.7, 132.2, 134.6, 137.2,
143.2, 143.3; IR (ATR) 2954, 2916, 2872, 2849, 1466, 871, 847, 736, 722, 712,
700, 645 cmꢁ1
;
HRMS (DART-ESI+) Calcd for C36H57S3 [M+H]+:585.3622;
Found: m/z 585.3608.
2,3-Bis(benzo[b]thiophen-2-yl)thiophene (3af)
1H NMR (CDCl3, 300 MHz) d 7.28 (d, J = 5.3 Hz, 1H), 7.27–7.37 (m, 5H), 7.39 (d,
J = 5.3 Hz, 1H), 7.42 (s, 1H), 7.69–7.80 (m, 4H); 13C NMR (CDCl3, 75 MHz) d
122.1 (ꢂ2), 123.4, 123.6, 123.7, 124.31, 124.33, 124.46, 124.48, 124.7, 125.6,
130.3, 132.66, 132.68, 135.1, 137.4, 139.6, 139.9, 140.1, 140.6; IR (ATR) 1260,
1155, 1091, 1020, 862, 798, 744, 724, 709, 696, 685 cmꢁ1; HRMS (DART-ESI+)
Calcd for C20H13S3 [M+H]+:349.0179; Found: m/z 349.0165.
2,3-Bis(benzo[b]furan-2-yl)thiophene (3ah)
1H NMR (CDCl3, 300 MHz) d 6.99 (s, 1H), 7.08 (s, 1H), 7.21–7.36 (m, 4H), 7.43
(d, J = 5.3 Hz, 1H), 7.48 (d, J = 5.3 Hz, 1H), 7.50 (d, J = 3.5 Hz, 1H), 7.53 (d,
J = 3.5 Hz, 1H), 7.57 (s, 1H), 7.59 (s, 1H); 13C NMR (CDCl3, 75 MHz) d 104.6,
105.3, 111.15, 111.19, 121.0, 121.1, 123.0, 123.2, 124.5, 124.8, 126.2, 128.81,
128.84, 128.9, 129.0, 129.1, 149.6, 151.5, 154.4, 154.6; IR (ATR) 1450, 1257,
1170, 1160, 1144, 1110, 1098, 1066, 1011, 946, 882, 863, 810, 799, 751, 739,
670, 660 cmꢁ1 HRMS (DART-ESI+) Calcd for C20H13O2S [M+H]+:317.0636;
;
Found: m/z 317.0642.
1,2-Bis(3-hexylthiophen-5-yl)benzene (3ea)
2,3-Bis(3-methylthiophen-5-yl)thiophene (3ac)
1H NMR (CDCl3, 300 MHz) d 0.89 (t, J = 6.7 Hz, 6H), 1.19–1.43 (m, 12H), 1.46–
1.63 (m, 4H), 2.52 (t, J = 7.5 Hz, 4H), 6.70 (d, J = 1.3 Hz, 2H), 6.84 (d, J = 1.3 Hz,
2H), 7.32 (dd, J = 3.4, 5.8 Hz, 2H), 7.48 (dd, J = 3.4, 5.8 Hz, 2H); 13C NMR (CDCl3,
75 MHz) d 14.1, 22.6, 28.9, 30.4, 30.5, 31.7, 120.4, 127.6, 128.5, 130.7, 134.0,
142.3, 143.1; IR (ATR) 2955, 2926, 2855, 1490, 1465, 1377, 1200, 1105, 1048,
984, 843, 760, 726, 651, 634 cmꢁ1; HRMS (DART-ESI+) Calcd for C26H35S2
[M+H]+:411.2180; Found: m/z 411.2187.
1H NMR (CDCl3, 300 MHz) d 2.23 (d, J = 0.9 Hz, 3H), 2.25 (d, J = 0.9 Hz, 3H),
6.82–6.86 (m, 1H), 6.89–6.91 (m, 2H), 6.95 (d, J = 1.3 Hz, 1H), 7.12 (d, J = 5.3 Hz,
1H), 7.23 (d, J = 5.3 Hz, 1H); 13C NMR (CDCl3, 75 MHz) d 15.65, 15.69, 120.7,
120.8, 122.0, 122.1, 124.1, 124.2, 128.7, 129.7, 130.1, 131.6, 132.1, 134.6, 137.2,
137.5, 137.6; IR (ATR) 1551, 1523, 1444, 1399, 1380, 1253, 1201, 142, 1090,
1031, 991, 875, 837, 797, 779, 737, 693, 645 cmꢁ1; HRMS (DART-ESI+) Calcd for
C
14H13S3 [M+H]+:277.0179; Found: m/z 277.0188.
Bis(30-hexyl-2,20-bithiophen-5-yl)dimethylsilane (3ga)
2,3-Bis(3-octylthiophen-5-yl)thiophene (3ad)
1H NMR (CDCl3, 300 MHz) d 0.64 (s, 6H), 0.88 (t, J = 6.6 Hz, 6H), 1.21–1.41 (m,
12H), 1.53–1.72 (m, 4H), 2.56 (t, J = 7.6 Hz, 4H), 6.80 (d, J = 1.3 Hz, 2H), 7.03 (d,
J = 1.3 Hz, 2H), 7.21 (s, 4H); 13C NMR (CDCl3, 75 MHz) d ꢁ0.29, 14.1, 22.6, 29.0,
30.3, 30.5, 31.7, 119.3, 124.8, 125.5, 136.16, 136.22, 136.7, 144.0, 144.1; IR
(ATR) 2955, 2926, 2855, 1461, 1453, 1416, 1252, 1215, 1191, 1071, 995, 854,
1H NMR (CDCl3, 300 MHz) d 0.88 (t, J = 6.6 Hz, 6H), 1.11–1.42 (m, 20H), 1.47–
1.68 (m, 4H), 2.47–2.63 (m, 4H), 6.83 (s, 1H), 6.87–6.92 (m, 2H), 6.96 (d,
J = 1.3 Hz, 1H), 7.13 (d, J = 5.3 Hz, 1H), 7.23 (d, J = 5.3 Hz, 1H); 13C NMR (CDCl3,
75 MHz) d 14.1, 22.7, 29.3, 29.41, 29.43, 30.40, 30.43, 31.9, 119.9, 121.2, 124.1,
127.7, 129.1, 129.6, 131.7, 132.2, 134.6, 137.1, 143.2, 143.3; IR (ATR) 2955,
2924, 2854, 1462, 1378, 1256, 1201, 1045, 840, 797, 725, 695, 645 cmꢁ1; HRMS
(DART-ESI+) Calcd for C28H41S3 [M+H]+:473.2370; Found: m/z 473.2358.
2,3-Bis(3-dodecylthiophen-5-yl)thiophene (3ae)
832, 799, 779, 738, 697, 676, 642 cmꢁ1
30H41S4Si [M+H]+:557.1860; Found: m/z 557.1875.
; HRMS (DART-ESI+) Calcd for
C
(5-Bromothiophen-2-yl)-(50-hexyl-2,20-bithiophen-5-yl)dimethylsilane (4ga)
1H NMR (CDCl3, 300 MHz) d 0.62 (s, 6H), 0.89 (t, J = 6.7 Hz, 3H), 1.21–1.39 (m,
6H), 1.56–1.69 (m, 2H), 2.57 (t, J = 7.6 Hz, 2H), 6.81 (d, J = 1.3 Hz, 1H), 7.03 (d,
J = 1.3 Hz, 1H), 7.06 (d, J = 3.5 Hz, 1H), 7.11 (d, J = 3.5 Hz, 1H), 7.18 (d, J = 3.5 Hz,
1H), 7.21 (d, J = 3.5 Hz, 1H).
1H NMR (CDCl3, 300 MHz) d 0.88 (t, J = 6.6 Hz, 6H), 1.61–1.41 (m, 36H), 1.50–
1.64 (m, 4H), 2.49–2.61 (m, 4H), 6.83 (s, 1H), 6.87–6.91 (m, 2H), 6.96 (d,
J = 1.3 Hz, 1H), 7.13 (d, J = 5.3 Hz, 1H), 7.23 (d, J = 5.3 Hz, 1H); 13C NMR (CDCl3,
75 MHz) d 14.1, 22.7, 29.3, 29.4, 29.48, 29.5, 29.63, 29.66, 29.70, 30.44, 30.45,