Oligothiophene S,S-Dioxides
J . Org. Chem., Vol. 63, No. 16, 1998 5505
3
3
Hz, 2H), 6.60 (d, J ) 4.7 Hz, 2H), 6.45 (doublet of triplets, J
) 4.7 Hz, 4J ) 1.8 Hz, 2H), 2.56 (t, 4H), 1.70 (m, 4H), 1.30 (m,
12H), 0.9 (m, 6H); 13C NMR (CDCl3, TMS/ppm) 144.1, 138.3,
135.9, 129.7, 128.9, 125.9, 122.5, 118.1, 31.4, 28.8, 26.7, 24.5,
22.5, 14.0. Anal. Calcd for C28H34O4S4: C, 59.75; H, 6.09.
Found: C, 59.83; H, 7.00.
gel using pentane/ethyl acetate 90:10. A total of 110 mg (50%
yield) of an orange powder, mp 172 °C, were recovered: MS
m/e 530 (M•+); λmax(CHCl3) 448 nm; 1H NMR (CDCl3, TMS/
3
3
ppm) 7.48 (d, J ) 4.0 Hz, 1H), 7.13 (d, J ) 4.0 Hz, 1H), 7.10
3
3
3
(d, J ) 3.8 Hz, 1H), 7.00 (d, J ) 4.0 Hz, 2 H), 6.69 (d, J )
3.8 Hz, 1H), 6.55 (d, 3J ) 4.9 Hz, 1H), 6.43 (doublet of triplets,
4
5-(n -Hexyl)-5′′-(tr ibu tylsta n n yl)-2,2′:5′,2′′-ter th iop h en e,
27. A solution containing 4.0 g (0.024 mol) of commercial 2,2′-
bithiophene and 4.5 mL (0.03 mol) of TMEDA in 80 mL of THF
was cooled to -70 °C, and 9.6 mL (0.024 mol) of BuLi 2.5 M
in hexane was added. After being stirred for a few minutes,
the solution was allowed to reach room temperature and then
stirred for 3 h. Then the solution was again cooled to -70 °C,
and 8.12 mL (0.03 mol) of Bu3SnCl was added dropwise. The
solution was allowed to reach rt and stirred overnight. After
usual workup, the yellow oil obtained was distilled (170 °C, 3
× 10-3 mmHg), and 8.74 g (80% yield) of a white oil identified
as 5-(tributylstannyl)-2,2′-bithiophene (compound 41 of Scheme
3J ) 4.9 Hz, J ) 1.8 Hz, 1H), 2.78 (t, 2H), 2.52 (t, 2H), 1.65
(m, 4H), 1.30 (m, 12H), 0.9 (m, 6H); 13C NMR (CDCl3, TMS/
ppm) 146.3, 143.6, 139.5, 138.4, 136.1, 134.1, 133.8, 128.8,
128.2, 125.8, 124.9, 124.3, 123.8, 123.6, 122.5, 117.0, 31.6, 31.4,
30.2, 28.8, 28.7, 26.8, 24.5, 22.6, 22.5, 14.1, 14.0. Anal. Calcd
for C28H34O2S4: C, 63.35; H, 6.46. Found: C, 63.17; H, 6.47.
5,5′′′′-Bis(dim eth yl-ter t-bu tylsilyl)-2,2′:5′,2′′:5′′,2′′′:5′′′,2′′′′-
qu in qu eth iop h en e 1′′,1′′-Dioxid e, 30. To a 5 mL toluene
solution of Pd(AsPh3)4 (0.01 mmol) prepared in situ4c were
added 0.05 g (0.18 mmol) of 2,5-dibromothiophene 1,1-dioxide
151d and 0.2 g (0.36 mmol) of 5-(dimethyl-tert-butylsilyl)-5′-
(tributylstannyl)-2,2′-bithiophene 18. After being refluxed for
4 h, the reaction mixture was filtered through silica gel using
petroleum ether for the first fraction and petroleum ether/
methylene chloride for the second one. After evaporation of
the solvent from the second fraction, the residue was washed
with ethyl ether, and 63 mg (52% yield) of a brown solid, mp
233-234 °C, was obtained: MS m/e 672 (M•+); λmax(CHCl3) 512
nm; 1H NMR (CDCl3, TMS/ppm) 7.54 (d, 3J ) 3.7 Hz, 2H),
3) was recovered: 1H NMR (acetone-d6, TMS/ppm) 7.39 (q, J
3
) 5.0, 4J ) 1.1 Hz, 1H), 7.36 (d, 3J ) 3.3 Hz, 1H),7.24 (q, 3J )
3
3
3
3.6, J ) 3.3 Hz, 1H), 7.15 (d, J ) 3.3 Hz, 1H), 7.06 (q, J )
3.6, 3J ) 3.3 Hz, 1H), 1.60 (m, 6H), 1.30 (m, 6H), 1.15 (m, 6H),
0.90 (t, 9H); 13C NMR (CDCl3, TMS/ppm) 137.5, 129.0, 126.1,
125.9, 125.8, 125.4, 124.9, 124.6, 29.9, 28.0, 13.6, 11.1.
To a solution of 1.00 g (2.22 mmol) of 41 in 8 mL of toluene
was added dropwise 1.08 g (4.39 mmol) of 2 dissolved in 10
mL toluene. After the mixture was stirred for a few minutes,
0.20 g (0.17 mmol) of commercial Pd(PPh3)4 was added and
the mixture refluxed overnight. After usual workup, 0.44 g
(60%) of a yellow powder identified as 5-(n-hexyl)-2,2′:5′,2′′-
terthiophene (compound 42 of Scheme 3), mp 48 °C, was
obtained: 1H NMR (CDCl3, TMS/ppm) 7.21 (doublet of dou-
blets, 3J ) 4.9 Hz, 4J ) 1.1 Hz, 1H), 7.13 (doublet of doublets,
3
3
3
7.30 (d, J ) 3.5 Hz, 2H), 7.21 (d, J ) 3.7 Hz, 2H), 7.16 (d, J
) 3.5 Hz, 2 H), 6.72 (s, 2H), 0.95 (s, 18H), 0.34 (s, 12H); 13C
NMR (CDCl3, TMS/ppm) 141.3, 140.3, 139.2, 136.1, 135.8,
129.0, 128.6, 126.1, 125.1, 117.9, 26.3, 16.9. Anal. Calcd for
C
32H40O2S5Si2: C, 57.10; H, 5.99. Found: C, 57.22; H, 6.00.
2-(Dim et h yl-ter t-b u t ylsilyl)-5-(t r ib u t ylst a n n yl)t h io-
p h en e, 31. To 30 mL of an ethyl ether solution of 5.07 g
(0.0256 mol) of 2-(dimethyl-tert-butylsilyl)thiophene4a was
added 10.3 mL (0.0257 mol) of BuLi 2.5 M in hexane at -10
°C. After the mixture was stirred for 1 h, an ethyl ether
solution of 6.39 mL (0.0256 mol) of Bu3SnCl was added to the
solution at room temperature and the mixture stirred over-
night. After usual workup, the crude product was distilled
(185 °C, 0.1 mmHg), and 10.60 g (85% yield) of 31 as a white
3J ) 3.6 Hz, J ) 1.1 Hz, 1H), 7.02 (d, J ) 3.5 Hz, 1H), 7.00
(doublet of doublets, J ) 3.6 Hz, J ) 4.9 Hz, 1H), 7.00 (d, J
) 3.5 Hz, 1H), 6.98 (d, J ) 3.5 Hz, 1H), 6.64 (d, J ) 5.0 Hz,
1H), 2.78 (t, 2H), 1.66 (t, 2H), 1.3 (m, 6H), 0.9 (t, 3H); 13C NMR
(CDCl3, TMS/ppm) 145.6, 137.3, 136.8, 135.5, 134.4, 127.8,
124.8, 124.3, 123.5, 123.4, 31.5, 30.2, 28.7, 22.5, 14.1.
4
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3
3
3
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1
To a solution of 1.00 g (0.003 mol) of 42 in 5 mL of THF and
containing 0.54 mL (0.0036 mol) of TMEDA was added 1.2 mL
(0.003 mol) of BuLi 2.5 M in hexane and 1.0 mL (0.0036 mol)
of Bu3SnCl at -10 °C. The temperature was then allowed to
rise to ambient and the mixture stirred overnight. After
solvent evaporation, the mixture was chromatographed on
aluminum oxide using petroleum ether 30-40 °C as the eluent.
A total of 0.51 g (27% yield) of 27 as a yellow oil was obtained.
oil was recovered: MS m/e 488 (M•+); H NMR (CDCl3, TMS/
3
3
ppm) 7.42 (d, J ) 3.6 Hz, 1H), 7.30 (d, J ) 3.6 Hz, 1H), 1.58
(m, 6H), 1.36 (m, 6H), 1.12 (t, 6H), 0.98 (s, 9H), 0.30 (s, 6H);
13C NMR (CDCl3, TMS/ppm) 142.8, 142.3, 136.0, 135.8, 29.0,
27.3, 26.5, 17.0, 13.7, 10.9, -4.6.
2,2′:5′,2′′-Ter th iop h en e 1′,1′-Dioxid e, 32. To a 12 mL
toluene solution containing 0.024 mmol of Pd(AsPh3)4 prepared
in situ4c was added 0.20 g (0.73 mmol) of 2,5-dibromothiophene
1,1-dioxide 15,1d 0.54 g (1.50 mmol) of 2-(tributylstannyl)-
thiophene 5 was added dropwise, and the mixture was stirred
overnight. The solvent was evaporated, and the crude product
was chromatographed on silica gel using petroleum ether/ethyl
alcohol 80:20. A total of 0.13 g (65% yield) of orange-red poly-
crystalline powder, 155 °C, was recovered: MS m/e 280 (M•+);
The product was used as such: MS m/e 622 (M•+); H NMR
1
3
3
(C6D6, TMS/ppm) 7.30 (d, J ) 3.3 Hz, 1H), 7.08 (d, J ) 3.3
3
3
Hz, 1H), 6.96 (d, J ) 3.7 Hz, 1H), 6.92 (d, J ) 3.6 Hz, 1 H),
3
3
6.88 (d, J ) 3.7 Hz, 1H), 6.47 (d, J ) 3.6 Hz, 1 H), 2.55 (t,
2H), 1.6 (m, 8H), 1.3 (m, 8 H), 1.2 (m, 10H), 0.9 (m, 12H); 13
C
NMR (C6D6, TMS/ppm) 145.5, 143.4, 137.1, 136.7, 136.5, 136.4,
135.3, 125.4, 125.2, 124.6, 124.1, 123.8, 31.9, 30.4, 29.4, 29.0,
27.6, 22.9, 14.2, 13.8, 11.2.
λ
max(CHCl3) 428 nm; 1H NMR (CDCl3, TMS/ppm) 7.65 (doublet
of doublets, 3J ) 4.0 Hz, 4J ) 1.2 Hz, 2H), 7.44 (doublet of
3
4
3
5,5′′′-Bis(d im et h yl-ter t-b u t ylsilyl)-2,2′:5′,2′′:5′′,2′′′-q u a -
ter th iop h en e 1,1-Dioxid e, 28. To an 8 mL toluene solution
containing 0.017 mmol of Pd(AsPh3)4 prepared in situ4c were
added 0.37 g (0.569 mmol) of 8 and 0.176 g (0.569 mmol) of 3.
After being refluxed for 6 h, the reaction mixture was
hydrolyzed with a saturated solution of NH4Cl and extracted
with CH2Cl2. The organic phase was dried over MgSO4,
concentrated, and filtered through silica gel.
After evaporation of the solvent, the residue was washed
with ethyl ether, and 0.163 g (49% yield) of 281a was recovered.
5,5′′′-Bis(n -h exyl)-2,2′:5′,2′′:5′′,2′′′-qu a ter th iop h en e 1,1-
Dioxid e, 29. To a 9 mL toluene solution containing 0.012
mmol of Pd(AsPh3)4 prepared in situ4c was added 260 mg (0.
42 mmol) of 5-(n-hexyl)-5′′-(tributylstannyl)-2,2′:5′,2′′-ter-
thiophene 27, and 120 mg (0.42 mmol) of 2-(n-hexyl)-5-
bromothiophene 1,1-dioxide 4 in 9 mL of toluene was added
dropwise. The mixture was refluxed overnight, treated with
a saturated solution of NH4Cl, and washed with water, and
the organic layer was separated, dried over MgSO4, and
evaporated. The crude product was chromatographed on silica
doublets, J ) 5.0 Hz, J ) 1.2 Hz, 2H), 7.15 (q, J ) 4.0 Hz,
3J ) 5.0 Hz, 2H), 6.78 (s, 2H); 13C NMR (CDCl3, TMS/ppm)
136.2, 129.8, 128.7, 128.2, 128.0, 118.6. Anal. Calcd for
C
12H8O2S3: C, 51.40; H, 2.88. Found: C, 51.21; H, 2.87.
5,5′′-Bis(d im e t h yl-t er t -b u t ylsilyl)-2,2′:5′,2′′-t e r t h io-
p h en e 1′,1′-Dioxid e, 33. A 0.01 mmol (12 mg) portion of
Pd2dba3 and 0.05 mmol (15 mg) of AsPh3 were dissolved in 10
mL of THF, and the solution was stirred for 30 min. Then a
solution containing 0.33 g (1.2 mmol) of 2,5-dibromothiophene
1,1-dioxide 151d and 1.16 g (2.4 mmol) of 2-dimethyl(tert-
butylsilyl)-5-(tributylstannyl)thiophene 31 was added drop-
wise, and the mixture was stirred for 6 h. The solvent was
evaporated, and the crude product was chromatographed on
silica gel using petroleum ether/ethyl alcohol 80:20. From
chromatography, two fractions were isolated. The first (105
mg, 17% yield) was a brown polycrystalline product, mp 199-
203 °C, identified as trimer 33. The second (160 mg, 34% yield)
was a yellow orange powder, mp 102-103 °C, identified as
5-(dimethyl-tert-butylsilyl)-5′-bromo-2,2′-bithiophene 1′,1′-
dioxide 33′.