Sulfur heterocyclization and 1,3-migration of silicon in reaction of 1,3-diynes with sodium triisopropylsilanethiolate: One-pot synthesis of 2,5-disubstituted 3-(triisopropylsilyl)thiophenes

Article abstract of DOI:10.1055/s-0033-1338472

Sulfur heterocyclization and 1,3-migration of silicon have been realized in the reactions of a range of 1,3-diynes with sodium triisopropylsilanethiolate in N,N-dimethylformamide. These provided 40-72% yields of 2,5-disubstituted 3-(triisopropylsilyl)thiophenes and up to 50% yield of 2,5-disubstituted thiophenes. Georg Thieme Verlag Stuttgart, New York.

Full text of DOI:10.1055/s-0033-1338472

PAPER
▌1713
paper
Sulfur Heterocyclization and 1,3-Migration of Silicon in Reaction of
1,3-Diynes with Sodium Triisopropylsilanethiolate: One-Pot Synthesis of
2,5-Disubstituted 3-(Triisopropylsilyl)thiophenes
Sulfur Heterocyclization
Jialiang Tang, Ling Ming, Xiaoming Zhao*
Department of Chemistry, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Siping Road 1239,
Shanghai 200092, P. R. of China
Fax +86(21)65981376; E-mail: xmzhao08@mail.tongji.edu.cn
Received: 14.03.2013; Accepted after revision: 02.04.2013
such as dimethyl sulfoxide, acetonitrile, toluene, tetrahy-
drofuran, and nitrobenzene were also screened (entries 3–
7).
Abstract: Sulfur heterocyclization and 1,3-migration of silicon
have been realized in the reactions of a range of 1,3-diynes with so-
dium triisopropylsilanethiolate in N,N-dimethylformamide. These
provided 40–72% yields of 2,5-disubstituted 3-(triisopropylsi-
lyl)thiophenes and up to 50% yield of 2,5-disubstituted thiophenes.
Table 1 Optimization of Metal-Free Sulfur Heterocyclization of 1,4-
Diphenylbuta-1,3-diyne (1a) with Sodium Triisopropylsilanethiolate
Key words: 1,3-diynes, cyclizations, 1,3-migration of silicon, thio-
phene, sulfur heterocycles
(2)a
TIPS
NaSTIPS
+
2
+
Ph
Ph
Ph
Ph
S
S
Silylated heteroaromatics are very important functional-
ities in materials displaying optical properties.1 Thio-
phenes with a silyl group (SiR3) can undergo significant
transformations for the preparation of functionalized thio-
phenes.2 Transition-metal-catalyzed heterocyclization of
1,3-diynes has also received great attention in the past de-
cades.3 In particular, five-membered heterocycles have
found various applications in medicine,4 agriculture,5 and
materials chemistry.6 Conventional methods for the syn-
thesis of silylated thiophenes require a metal catalyst,
thiophene, and silicon reagent.6c,7 Recently Nakamura and
co-workers reported a gold-catalyzed intramolecular
cyclization and a [1,3]-migration of a silyl group of
(o-alkynylphenylsulfanyl)silanes, producing silylated
thiophenes.8 To date, metal-free cyclization and 1,3-mi-
gration of silicon in the reaction between a 1,3-diyne and
a sulfur nucleophile has not been explored. In this paper,
we report the first one-pot synthesis of 2,5-disubstituted
3-(triisopropylsilyl)thiophenes by means of sulfur hetero-
cyclization and a 1,3-migration of triisopropylsilyl in the
reactions of various 1,3-diynes with sodium triisopropyl-
silanethiolate (NaSTIPS; 2).
Ph
Ph
1a
3a
4a
Entry Solvent Ratio
Temp Time Yield of
Yield of
1a/2
(°C)
(h)
3a (%)b
4a (%)b
1
2
DMF
DMF
DMSO
MeCN
toluene
THF
1:1.2
1:1.2
1:1.2
1:1.2
1:1.2
1:1.2
1:1.2
1:1.2
1:1.2
1:1.2
1:1.2
1:2
25
50
18
18
18
18
18
18
18
18
18
18
18
1
–
trace
10
13c
trace
–
–
3
50
–
4
50
–
5
50
–
6
50
–
–
7
PhNO2
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
50
–
–
8
75
–
11
14
29
32
55
69
33
46
–
9
100
125
150
150
150
125
150
150
3
10
11
12
13
14
15d
16e
15
25
44
30
18
52
–
We began with the investigation of the reaction between
1,4-diphenylbuta-1,3-diyne (1a) and sodium triisopropyl-
silanethiolate (2) to form a silylated thiophene (Table 1).
First, the reaction of 1a with sodium triisopropylsilaneth-
iolate (2) in the absence of transition metal7 in N,N-di-
methylformamide was tested at room temperature under
an air atmosphere; this led to the formation of a trace
amount of 2,5-diphenylthiophene (4a)9 (entry 1). When
the temperature was increased to 50 °C, the yield of this
reaction improved slightly (entry 2). Various solvents
1:3
1
2:1
18
1
1:2
1:2
1
a Reaction conditions: 1a (0.2 mmol), 2 (0.2–0.6 mmol), solvent (2.0
mL), under air.
b Isolated yield.
c Two other byproducts were obtained.
d Under argon.
e HSTIPS was used instead of NaSTIPS under argon.
SYNTHESIS 2013, 45, 1713–1718
Advanced online publication: 08.05.2013
0
0
3
9
-
7
8
8
1
1
4
3
7
-
2
1
0
X
DOI: 10.1055/s-0033-1338472; Art ID: SS-2013-H0207-OP
© Georg Thieme Verlag Stuttgart · New York

1714
J. Tang et al.
PAPER
We found that N,N-dimethylformamide and dimethyl
sulfoxide both gave 4a in 10–13% yield, and dimethyl
sulfoxide gave some byproducts, whereas other solvents
were ineffective for this reaction (Table 1, entries 4–7).
To study the influence of temperature on this reaction, we
performed this reaction at a range of temperatures, from
50 to 150 °C (entries 2, 8–12). When the reaction temper-
ature was increased from 75 to 100 °C, 2,5-diphenyl-3-
(triisopropylsilyl)thiophene (3a)10 was also observed (en-
try 9). These results suggested that a [1,3]-migration of
triisopropylsilyl occurred during the course of the reac-
tion.8a When the reaction was carried out at 150 °C, 25%
yield of 3a and 32% yield of 4a were obtained upon com-
pletion of the reaction (entry 11). Variation of the ratio of
1a/2 has a considerable influence on the efficiency of this
reaction. Excess of 2 led to improvement in the formation
of 4a (entries 12, 13). Two equivalents of 2 resulted in a
superior yield of 3a and a 55% yield of 4a (entry 12). No-
tably, when the same reaction was carried out under ar-
gon, a 52% yield of 3a and 46% yield of 4a were obtained
(entry 15). These results indicated that moisture has a con-
siderable influence on the formation of 4a (entry 12 vs.
15). We found that it is difficult to suppress the formation
of 4a during the reaction. A control experiment revealed
that 3a cannot be converted into 4a under the identical re-
action conditions. However, both 3a and 4a are of great
importance in material chemistry.1,2 This reaction com-
pletely failed when triisopropylsilanethiol was used as a
nucleophile instead of sodium triisopropylsilanethiolate
(entry 16).11 Moreover, different silanethiolates, such as
sodium triphenylsilanethiolate, were also explored under
the same conditions, and only 4a was obtained.
Table 2 Sulfur Heterocyclization and 1,3-Migration of Triisopro-
pylsilyl of 1,3-Diynes 1 with Sodium Triisopropylsilanethiolate (2)a
TIPS
NaSTIPS
+
2
DMF
+
150 °C
R
R
R
R
R
R
S
S
1
3
4
Entry
R
Time
(h)
Yield of 3 Yield of 4
(%)b
(%)b
1
2
3
4
5
6
7
8
9
Ph
1
1
2
2
1
1
1
1
1
3a, 52
3b, 55
3c, 43
3d, 49
3e, 69
3f, 53
3g, 53
3h, 72
3i, 40
4a, 46
4b, 44
4c, 46
4d, 50
4e, trace
4f, 46
3-MeC6H4
4-MeC6H4
4-Me(CH2)4C6H4
4-PhC6H4
4-BrC6H4
4-FC6H4
4g, 45
4h, 21
4i, 34
2-thienyl
3-thienyl
a Reaction conditions: 1 (0.2 mmol), 2 (0.4 mmol), DMF (2.0 mL),
150 °C, under argon.
b Isolated yield.
demonstrated in Scheme 1. The reaction of 1-phenyl-4-
(trimethylsilyl)buta-1,3-diyne (1j)12 with sodium triiso-
propylsilanethiolate (2) under the optimized conditions
afforded 2-phenyl-4-(triisopropylsilyl)thiophene (3j) in
37% yield (Scheme 1). Favorable attack of sodium triiso-
propylsilanethiolate at the 4-position of 1j depends on the
nature of the polarized conjugated system of 1j. Removal
of trimethylsilyl from either the thiophene ring or 1j may
occur in this case, possibly resulting from the use of an ex-
cess of sodium triisopropylsilanethiolate.13 Experimental
evidence supporting this hypothesis is that the reaction be-
tween buta-1,3-diynylbenzene (generated by desilylation
of 1j with KOH/MeOH under reflux) and sodium triiso-
propylsilanethiolate (2) under the optimized conditions
gave 3j, but in 8% yield. Indeed, no 2-phenyl-3-(triisopro-
pylsilyl)thiophene (4j) was obtained in this case (Scheme
1).
The scope of the sulfur heterocyclization and 1,3-migra-
tion of triisopropylsilyl in the reactions of various 1,3-
diynes 1 with sodium triisopropylsilanethiolate (2) was
then studied. As shown in Table 2, the reactions of 1,3-
diynes 1a–g with electron-donating (e.g., 3-methyl, 4-
methyl, 4-pentyl, and 4-phenyl) or electron-withdrawing
(e.g., 4-bromo and 4-fluoro) groups on the phenyl ring
furnished 2,5-disubstituted 3-(triisopropylsilyl)thio-
phenes 3a–g in 43–69% yields; trace to 50% yields of 4a–
g were also obtained (entries 1–7). Compound 4d may
find application as a liquid crystal.6b Both 3f and 4f con-
tain the 4-bromophenyl group, which could be used in pal-
ladium-mediated couplings. The steric factor at the 4-
position of aryl-substituted 1,3-diynes has a great influ-
ence on the chemoselectivity of this reaction. For exam-
ple, 1e bearing a phenyl group at the 4-position of the
phenyl ring gave the corresponding 3e as the major prod-
uct (69% yield) along with a trace amount of 4e (entry 5).
When 1,4-bis(2-thienyl)-substituted 1h was utilized as the
substrate, it gave rise to 72% yield of 3h and 21% yield of
4h (entry 8). In contrast, the reaction of 1,4-bis(3-thienyl)-
substituted 1i gave 40% yield of 3i along with 34% yield
of 4i (entry 9). It is noteworthy that either 3 or 4 may dis-
play fluorescence.9,10
TIPS
TIPS
NaSTIPS
+
2
DMF
+
150 °C, 3 h
Ph
Ph
SiMe3
Ph
S
S
1j
3j
4j
37%
Scheme 1 Sulfur heterocyclization and 1,3-migration of triisopro-
pylsilyl of 1j with sodium triisopropylsilanethiolate (2)
The possible application of these compounds in the area
of materials was investigated. The photophysical proper-
ties of 3a, 3d, 3g, and 3h were studied by using UV-vis
and photoluminescence (PL) spectroscopy. The results
are shown in Figures 1 and 2. The λmax values of both 3d
An unsymmetrical 1,3-diyne was also investigated as a
substrate in this reaction and a representative example is
Synthesis 2013, 45, 1713–1718
© Georg Thieme Verlag Stuttgart · New York

PAPER
Sulfur Heterocyclization
1715
and 3g blue-shifted by at least 17 nm compared with that
of 3a. These results reveal that the introduction of either
fluoro or n-pentyl in the phenyl ring considerably reduce
the conjugation effect of 3a. Maximum absorption wave-
length (λabs(max)) values, emission maximum (λem(max)), and
Stokes shift of 3a, 3d, 3g, and 3h are listed in Table 3. In
comparison with that of the known 4h (λmax = 354 nm),14
the λmax value of 3h blue-shifted by 53 nm, which results
from the introduction of a triisopropylsilyl group to the
thiophene ring (Figure 1 and Table 3).
Figure 2 Fluorescence spectra of 3a, 3d, 3g, and 3h in ethyl acetate
1H and 13C NMR spectra were recorded using a Bruker AM-400
spectrometer; samples were prepared in CDCl3 with TMS as an in-
ternal standard. 19F NMR spectra were obtained at 376 MHz, and
CF3CO2H was used as internal standard. Mass spectra were ob-
tained on an Agilent 5973N spectrometer. Melting points were re-
corded by using a WRS-2A micro-melting-point apparatus and are
uncorrected. A Nicolet AVATAR 360 FT-IR spectrophotometer
was used for IR spectra. UV-vis spectra were recorded on an Agile-
nt 8453 spectrometer at r.t.; samples were prepared as diluted
EtOAc solns. Photoluminescence spectra were recorded on a
Hituchi F-2700 luminescence spectrometer; samples were diluted
EtOAc solns. Analytical TLC was performed on glass plates pre-
coated with GF 254 silica gel impregnated with fluorescent indica-
tor. All manipulations were carried out under an argon atmosphere
and by using standard Schlenk techniques, unless stated otherwise.
All glassware was oven- or flame-dried immediately prior to use.
All solvents were purified and dried according to standard methods
prior to use, unless stated otherwise.
Figure 1 UV-vis spectra of 3a, 3d, 3g, and 3h in ethyl acetate
Table 3 Optical Absorption Wavelength [λabs(max)], Fluorescence
Emission Wavelength [λem(max)], and Stokes Shifts for 3a, 3d, 3g, and
3h
Compound
λ
abs(max), nm
λem(max), nm
Stokes shift,a nm
3a
3d
3g
3h
350
333
293
301
439
405
395
397
89
72
Thiophenes 3a–j and 4a–i; General Procedure
The appropriate 1,3-diyne 1 (0.2 mmol) and NaSTIPS (2; 0.4 mmol)
were dissolved in DMF (2 mL) in a dry Schlenk tube filled with ar-
gon. The reaction mixture was stirred at 150 °C for 1–2 h. After
completion of the reaction, as indicated by TLC, the mixture was
quenched by the addition of brine (20 mL), and then extracted with
Et2O (3 × 5 mL). The combined organic layer was dried (Na2SO4).
The solvent was evaporated and the crude product was purified by
column chromatography (silica gel, PE); this gave thiophenes 3 and
4 as products. The 1,3-diynes15 and NaSTIPS16 were prepared ac-
cording to known procedures.
102
96
a The Stokes shift is the difference between λabs(max) and λem(max)
.
The fluorescence emission wavelength (λem(max)) data of
3a, 3d, 3g, and 3h (Figure 2 and Table 3) showed a similar
trend to that of the absorption wavelength (λabs(max)) data
of these compounds. Compound 3a exhibited the highest
2,5-Diphenyl-3-(triisopropylsilyl)thiophene (3a)
Yield: 41.1 mg (52%); colorless oil.
λ
em(max) value and 3g showed the largest Stokes shift (Ta-
ble 3).
IR (KBr): 513, 639, 669, 705, 741, 762, 1143, 1264, 1457, 2849,
2877, 2973 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.00 (d, J = 7.2 Hz, 18 H), 1.11–
1.17 (m, 3 H), 7.24–7.39 (m, 7 H), 7.48 (d, J = 7.6 Hz, 2 H), 7.60
(d, J = 7.6 Hz, 2 H).
In summary, we have developed a convenient method for
the preparation of 2,5-disubstituted 3-(triisopropylsi-
lyl)thiophenes by sulfur heterocyclization and 1,3-migra-
tion of silicon during the reactions of various 1,3-diynes
with sodium triisopropylsilanethiolate. To the best of our
13C NMR (100 MHz, CDCl3): δ = 12.3, 18.9, 125.9, 127.2, 127.5,
knowledge, this is the first reported method for the synthe- 128.1, 128.8, 130.4, 130.7, 133.9, 134.4, 136.6, 143.2, 151.2.
ESI-MS: m/z = 392 [M]+.
HRMS (ESI): m/z [M]+ calcd for C25H32SSi: 392.1994; found:
sis of 2,5-disubstituted 3-(triisopropylsilyl)thiophenes
from 1,3-diynes.
392.1990.
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2013, 45, 1713–1718

1716
J. Tang et al.
PAPER
2,5-Di(m-tolyl)-3-(triisopropylsilyl)thiophene (3b)
1H NMR (400 MHz, CDCl3): δ = 1.00 (d, J = 6.8 Hz, 18 H), 1.11–
1.18 (m, 3 H), 7.26 (s, 1 H), 7.34 (d, J = 8.8 Hz, 2 H), 7.44 (d,
J = 8.8 Hz, 2 H); 7.47–7.51 (m, 4 H).
13C NMR (100 MHz, CDCl3): δ = 12.3, 18.9, 121.2, 122.6, 127.4,
130.8, 131.2, 131.8, 132.0, 133.1, 134.7, 135.4, 142.4, 149.9.
Yield: 46.3 mg (55%); colorless oil.
IR (KBr): 668, 706, 741, 789, 1264, 1653, 2878 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.00 (d, J = 7.2 Hz, 18 H), 1.10–
1.19 (m, 3 H), 2.36 (s, 3 H), 2.39 (s, 3 H), 7.07 (d, J = 7.6 Hz, 1 H),
7.16 (d, J = 7.6 Hz, 1 H), 7.20–7.31 (m, 5 H), 7.41 (s, 2 H).
ESI-MS: m/z = 550 [M + 2]+.
13C NMR (100 MHz, CDCl3): δ = 12.3, 18.9, 21.3, 21.4, 123.1,
126.7, 127.4, 127.4, 128.0, 128.7, 128.8, 130.6, 131.1, 133.6, 134.4,
136.5, 137.0, 138.4, 143.1, 151.3.
ESI-MS: m/z = 420 [M]+.
HRMS (ESI): m/z [M]+ calcd for C27H36SSi: 420.2307; found:
HRMS (ESI): m/z [M]+ calcd for C25H30Br2SSi: 548.0204; found:
548.0209.
2,5-Bis(4-fluorophenyl)-3-(triisopropylsilyl)thiophene (3g)
Yield: 45.4 mg (53%); mp 107–108 °C.
IR (KBr): 516, 624, 678, 1234, 1385, 1457, 1496, 1507, 1559, 1636,
2050 cm–1.
420.2306.
2,5-Di(p-tolyl)-3-(triisopropylsilyl)thiophene (3c)
1H NMR (400 MHz, CDCl3): δ = 1.00 (d, J = 7.6 Hz, 18 H), 1.08–
1.16 (m, 3 H), 7.01–7.09 (m, 4 H), 7.20 (s, 1 H), 7.42–7.46 (m, 2 H),
7.53–7.56 (m, 2 H).
Yield: 36.2 mg (43%); mp 101–103 °C.
IR (KBr): 453, 518, 1507, 1540, 1559, 1636, 1653, 1683 cm–1.
13C NMR (100 MHz, CDCl3): δ = 12.2, 18.9, 114.5 (JC-F = 21 Hz),
115.8 (JC-F = 21 Hz), 127.5, 127.6, 130.5, 130.6, 132.0, 132.1,
132.4, 132.5, 134.5, 142.3, 149.7, 162.2 (JC-F = 246 Hz), 162.8
(JC-F = 246 Hz).
19F NMR (376 MHz, CDCl3): δ = –113.55, –114.84.
ESI-MS: m/z = 428 [M]+.
1H NMR (400 MHz, CDCl3): δ = 1.00 (d, J = 7.2 Hz, 18 H), 1.10–
1.19 (m, 3 H), 2.36 (s, 3 H), 2.39 (s, 3 H), 7.13 (d, J = 7.6 Hz, 2 H),
7.17 (d, J = 8.0 Hz, 2 H), 7.24 (s, 1 H), 7.36 (d, J = 8.0 Hz, 2 H),
7.48 (d, J = 8.0 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 12.3, 18.9, 21.2, 21.3, 125.8,
128.2, 129.5, 130.2, 131.7, 133.4, 133.7, 136.9, 137.8, 143.1, 150.9.
ESI-MS: m/z = 420 [M]+.
HRMS (ESI): m/z [M]+ calcd for C25H30F2SSi: 428.1806; found:
HRMS (ESI): m/z [M]+ calcd for C27H36SSi: 420.2307; found:
428.1807.
420.2303.
2,5-Bis(2-thienyl)-3-(triisopropylsilyl)thiophene (3h)
Yield: 58.3 mg (72%); colorless oil.
2,5-Bis(4-pentylphenyl)-3-(triisopropylsilyl)thiophene (3d)
Yield: 52.2 mg (49%); colorless oil.
IR (KBr): 787, 1559, 1636, 2863, 2959 cm–1.
IR (KBr): 563, 740, 824, 1019, 1130, 1263, 1472, 1541, 1653, 2877,
2978 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.04 (d, J = 7.2 Hz, 18 H), 1.20–
1.29 (m, 3 H), 6.99 (d, J = 4.0 Hz, 1 H), 7.01 (d, J = 4.0 Hz, 1 H),
7.13–7.14 (m, 2 H), 7.15 (s, 1 H), 7.20 (d, J = 6.0 Hz, 1 H), 7.32 (d,
J = 6.0 Hz, 1 H).
1H NMR (400 MHz, CDCl3): δ = 0.90 (t, J = 6.8 Hz, 6 H), 0.99 (d,
J = 7.2 Hz, 18 H), 1.13–1.16 (m, 3 H), 1.30–1.34 (m, 8 H), 1.61–
1.66 (m, 4 H), 2.59–2.66 (m, 4 H), 7.13 (d, J = 7.6 Hz, 2 H), 7.17
(d, J = 8.0 Hz, 2 H), 7.24 (s, 1 H), 7.37 (d, J = 8.0 Hz, 2 H), 7.50 (d,
J = 8.0 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 12.4, 19.0, 123.9, 124.3, 126.6,
13C NMR (100 MHz, CDCl3): δ = 12.3, 13.4, 13.5, 14.0, 14.0, 18.1,
18.3, 18.9, 31.0, 31.1, 31.3, 31.5, 125.8, 127.5, 128.8, 130.2, 130.2,
131.9, 133.6, 133.9, 142.0, 142.9, 143.0, 150.9.
127.8, 128.8, 131.4, 136.8, 136.8, 136.9, 137.5, 141.4.
ESI-MS: m/z = 404 [M]+.
HRMS (ESI): m/z [M]+ calcd for C21H28S3Si: 404.1122; found:
404.1127.
ESI-MS: m/z = 532 [M]+.
HRMS (ESI): m/z [M]+ calcd for C35H52SSi: 532.3559; found:
532.3553.
2,5-Bis(3-thienyl)-3-(triisopropylsilyl)thiophene (3i)
Yield: 32.4 mg (40%); mp 84–86 °C.
2,5-Bis(biphenyl-4-yl)-3-(triisopropylsilyl)thiophene (3e)
Yield: 75.2 mg (69%); mp 170–172 °C.
IR (KBr): 514, 654, 676, 706, 740, 773, 839, 1141, 1264, 1636,
2069, 2864, 2944 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.02 (d, J = 7.2 Hz, 18 H), 1.13–
1.22 (m, 3 H), 7.16–7.17 (m, 2 H), 7.27–7.35 (m, 5 H).
IR (KBr): 442, 516, 738, 1264, 1507, 1521, 1541, 1559, 1636, 2053
cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.03 (d, J = 7.2 Hz, 18 H), 1.16–
1.23 (m, 3 H), 7.33–7.39 (m, 3 H), 7.45 (d, J = 7.6 Hz, 2 H), 7.48
(d, J = 7.2 Hz, 2 H), 7.56–7.63 (m, 8 H), 7.67 (d, J = 7.2 Hz, 2 H),
7.69 (d, J = 8.4 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 12.4, 19.0, 126.2, 126.3, 126.9,
127.0, 127.3, 127.5, 127.5, 128.8, 128.8, 130.7, 130.9, 133.4, 134.2,
135.6, 140.0, 140.5, 140.6, 140.8, 142.9, 150.9.
13C NMR (100 MHz, CDCl3): δ = 12.3, 18.9, 119.4, 124.6, 124.8,
126.2, 126.2, 130.1, 130.7, 134.4, 135.4, 136.4, 138.0, 144.0.
ESI-MS: m/z = 404 [M]+.
HRMS (ESI): m/z [M]+ calcd for C21H28S3Si: 404.1122; found:
404.1125.
2-Phenyl-4-(triisopropylsilyl)thiophene (3j)
Yield: 23.4 mg (37%); colorless oil.
ESI-MS: m/z = 544 [M]+.
HRMS (ESI): m/z [M]+ calcd for C37H40SSi: 544.2620; found:
544.2618.
IR (KBr): 487, 668, 691, 717, 731, 766, 1154, 1237, 1492, 2861,
2884, 2948 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.10 (d, J = 7.2 Hz, 18 H), 1.31–
1.39 (m, 3 H), 7.26 (t, J = 7.2 Hz, 1 H), 7.33–7.39 (m, 4 H), 7.62 (d,
J = 7.2 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 11.4, 18.7, 126.2, 127.2, 128.8,
128.9, 132.4, 134.6, 137.1, 144.3.
2,5-Bis(4-bromophenyl)-3-(triisopropylsilyl)thiophene (3f)
Yield: 58.4 mg (53%); mp 136–137 °C.
IR (KBr): 655, 669, 1345, 1612, 1631, 1641, 1659, 2342, 2360
cm–1.
ESI-MS: m/z = 316 [M]+.
Synthesis 2013, 45, 1713–1718
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Sulfur Heterocyclization
1717
HRMS (ESI): m/z [M]+ calcd for C19H28SSi: 316.1681; found:
316.1684.
Acknowledgment
We gratefully acknowledge the NSFC (21272175 and 201242003)
for generous financial support.
2,5-Diphenylthiophene (4a)17
Yield: 21.7 mg (46%); mp 148–150 °C.
IR (KBr): 685, 749, 804, 903, 944, 1079, 1326, 1457, 1640, 1873,
1934, 2847, 2914, 2956 cm–1.
References
1H NMR (400 MHz, CDCl3): δ = 7.30 (dd, J = 7.6, 7.2 Hz, 2 H),
7.31 (s, 2 H), 7.41 (dd, J = 8.0, 7.2 Hz, 4 H), 7.65 (d, J = 8.0 Hz, 4
H).
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F.; Anthony, J. E. Angew. Chem. Int. Ed. 2011, 50, 7013.
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2,5-Di(m-tolyl)thiophene (4b)18
Yield: 23.3 mg (44%); mp 83–85 °C.
IR (KBr): 592, 685, 778, 813, 1454, 1582, 1604, 2844, 2917, 2962
cm–1.
1H NMR (400 MHz, CDCl3): δ = 2.40 (s, 6 H), 7.10 (d, J = 7.2 Hz,
2 H), 7.28 (dd, J = 9.2, 6.8 Hz, 2 H), 7.27 (s, 2 H), 7.44 (d, J = 7.6
Hz, 2 H), 7.45 (s, 2 H).
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95, 1009. (c) Cunico, R. F.; Bedell, L. J. Org. Chem. 1980,
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2,5-Di(p-tolyl)thiophene (4c)19
Yield: 24.3 mg (46%); mp 170–172 °C.
IR (KBr): 467, 797, 826, 938, 1066, 1130, 1454, 1556, 1649, 1771,
1899, 2853, 2914, 2966 cm–1.
1H NMR (400 MHz, CDCl3): δ = 2.36 (s, 6 H), 7.18 (d, J = 8.0 Hz,
4 H), 7.22 (s, 2 H), 7.51 (d, J = 8.0 Hz, 4 H).
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2,5-Bis(4-pentylphenyl)thiophene (4d)20
Yield: 37.6 mg (50%); mp 132–134 °C.
IR (KBr): 514, 745, 796, 835, 889, 937, 1011, 1081, 1120, 1261,
1415, 1450, 1498, 1540, 2850, 2930, 2955, 3052 cm–1.
1H NMR (400 MHz, CDCl3): δ = 0.90 (t, J = 6.4 Hz, 6 H), 1.29–1.41
(m, 8 H), 1.57–1.70 (m, 4 H), 2.61 (t, J = 7.6 Hz, 4 H), 7.19 (d,
J = 8.0 Hz, 4 H), 7.23 (s, 2 H), 7.53 (d, J = 8.0 Hz, 4 H).
2,5-Bis(4-bromophenyl)thiophene (4f)21
Yield: 36.2 mg (46%); mp 202–203 °C.
IR (KBr): 467, 746, 791, 826, 935, 1117, 1262, 1332, 1399, 1447,
1559, 1627, 1652, 1774, 1899 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.27 (s, 2 H), 7.47 (d, J = 8.8 Hz,
4 H), 7.51 (d, J = 8.4 Hz, 4 H).
2,5-Bis(4-fluorophenyl)thiophene (4g)22
Yield: 24.5 mg (45%); mp 159–160 °C.
(7) (a) For a review, see: Yamamoto, Y. Chem. Rev. 2008, 108,
3199. (b) Brand, J. P.; Waser, J. Angew. Chem. Int. Ed. 2010,
49, 7304. (c) Chen, L.; Roger, J.; Bruneau, C.; Dixneuf, P.
H.; Doucet, H. Chem. Commun. 2011, 47, 1872.
IR (KBr): 493, 551, 707, 733, 794, 836, 896, 938, 1101, 1265, 1300,
1412, 1457, 1502, 1521, 1652, 1764, 1886, 2847, 2917, 2988, 3052,
3078 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.06–7.11 (m, 4 H), 7.20 (s, 2 H),
7.55–7.59 (m, 4 H).
19F NMR (376 MHz, CDCl3): δ = –114.30.
(d) Yamanoi, Y.; Nishihara, H. J. Org. Chem. 2008, 73,
6671.
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Lett. 2007, 9, 4081. Related studies on silicon migration
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G.; Clot, E.; Cowley, A. R.; Gade, L. H.; Mountford, P.
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Nakamura, K.; Shiota, Y.; Yoshizawa, K.; Kawauchi, S.;
Ishikawa, M. J. Am. Chem. Soc. 1997, 119, 807.
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2,5-Bis(2-thienyl)thiophene (4h)23
Yield: 10.4 mg (21%); mp 120–121 °C.
IR (KBr): 468, 703, 738, 807, 822, 843, 1264, 1636, 1653, 2363
cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.02 (d, J = 3.6 Hz, 1 H), 7.03 (d,
J = 4.0 Hz, 1 H), 7.08 (s, 2 H), 7.17 (d, J = 0.8 Hz, 1 H), 7.18 (d,
J = 0.8 Hz, 1 H), 7.21 (d, J = 0.8 Hz, 1 H), 7.22 (d, J = 1.2 Hz, 1 H).
2,5-Bis(3-thienyl)thiophene (4i)24
Yield: 16.9 mg (34%); mp 189–190 °C.
IR (KBr): 462, 714, 753, 827, 834, 851, 1189, 1574, 1683, 2257,
2386 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.12 (s, 2 H), 7.31 (d, J = 5.2 Hz,
1 H), 7.32 (d, J = 5.2 Hz, 1 H), 7.34–7.38 (m, 4 H).
© Georg Thieme Verlag Stuttgart · New York
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J. Tang et al.
PAPER
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Synthesis 2013, 45, 1713–1718
© Georg Thieme Verlag Stuttgart · New York