New 1,4-Bis(alkylthio)-3,6-diarylthieno[3,4-c]thiophenes
J . Org. Chem., Vol. 63, No. 1, 1998 167
tetramethylsilane (TMS) as an internal standard. Column
chromatography was performed on silica gel (Wakogel C-300).
P r ep a r a t ion of Cyclop r op en et h ion es 1a -h . Com-
pounds 1a ,b and 1d -h were prepared according to the
methods described previously.6-8 Compound 1c was prepared
from 2,3-bis(tert-butylthio)cyclopropenethione and (2,4,6-tri-
isopropylphenyl)lithium by the procedure similar to that in
the preparation of 1a .
2-(ter t-Bu tylth io)-3-(2,4,6-tr iisopr op ylph en yl)cyclop r o-
p en eth ion e (1c): pale yellow crystals; yield 22%; mp 106-
108 °C (methanol); 1H NMR δ 1.26 (d, 12 H, J ) 6.7 Hz), 1.28
(d, 6 H, J ) 7.3 Hz), 1.80 (s, 9 H), 2.94 (sep, 1 H, J ) 7.3 Hz),
3.82 (sep, 2 H, J ) 6.7 Hz), 7.13 (s, 2 H); IR (KBr) 2958, 1716,
1597, 1455 cm-1; UV (hexane) λmax (nm) (log ꢀ) 326 (4.18), 271
(4.21). Anal. Calcd for C22H32S2: C, 73.28; H, 8.94. Found:
C, 73.30; H, 9.13.
spectrum of the solution was recorded immediately. The 1H
NMR spectrum showed peaks for the salt 16a at δ 0.99 (s, 9
H, 4-SBut), 1.06 (s, 9 H, 1-SBut), 5.93 (s, 1 H, 3-H) and 7.01-
7.35 (m, 10 H, 3,6-Ph). This spectrum changed to that of 13a
on keeping the sample tube at room temperature for 20 h.
Rea ction of 2a w ith TF A in th e P r esen ce of Wa ter . To
a solution of 2a (0.2 mmol) in dry benzene (10 mL) were added
TFA (0.6 mmol) and water (2 mmol) under argon, and the
mixture was stirred at room temperature for 20 h. After
removal of the solvent under reduced pressure, the residue
was purified by column chromatography with toluene-hexane
(1:1) as eluent to give 14.
4-(ter t-Bu tylth io)-3,6-d ip h en ylth ien o[3,4-c]th iop h en e-
1(3H)-on e (14): white crystals; yield 88%; mp 154-155.5 °C
1
(methanol); H NMR δ 1.20 (s, 9 H), 5.72 (s, 1 H), 7.28-7.46
(m, 8 H), 7.80-7.83 (m, 2 H); IR (KBr) 1680, 1518, 1455 cm-1
;
UV (hexane) λmax (nm) (log ꢀ) 340 (4.08), 280 (3.99). Anal.
Calcd for C22H20OS3: C, 66.63; H, 5.08. Found: C, 66.38; H,
4.96.
Gen er a l P r oced u r e for th e Rea ction s of Cyclop r o-
p en eth ion es 1a -h w ith Tr ip h en ylp h osp h in e. To a solu-
tion of 1a -h (1 mmol) in dry benzene (20 mL) was added
triphenylphosphine (0.5 mmol) under argon, and the mixture
was stirred at 50 °C for 20 h. After removal of the solvent
under reduced pressure, the residue was subjected to column
chromatography with toluene-hexane (1:1) as eluent. Com-
pounds 2a ,b and 3 were isolated, but 1c-g were recovered
unchanged (96-98% recoveries).
1,4-B is (t er t -b u t y lt h io )-3,6-d ip h e n y lt h ie n o [3,4-c]-
th iop h en e (2a ): red crystals; yield 46%; mp 177-178.5 °C
dec (methanol); 1H NMR δ 0.94 (s, 18 H), 7.34-7.45 (m, 6 H),
7.67-7.71 (m, 4 H); 13C NMR δ 30.17, 49.34, 110.30, 127.51,
127.61, 130.76, 131.45, 132.5, 147.78; IR (KBr) 1455, 1362
cm-1; UV (hexane) λmax (nm) (log ꢀ) 515.5 (4.34), 294.5 (4.36),
280.0 (4.31), 247.5 (4.34). Anal. Calcd for C26H28S4: C, 66.62;
H, 6.02. Found: C, 66.55; H, 6.04.
Alk yla tion of 13a w ith Isop r op yl Iod id e. A solution of
13a (0.2 mmol) in dry DMF (10 mL) was added under argon
to a suspension of sodium hydride (60% mineral oil dispersion)
(0.4 mmol) in DMF (5 mL) at room temperature. The mixture
was stirred for 30 min, and then isopropyl iodide (0.4 mmol)
was added. After being stirred for 30 min, the mixture was
poured into water and extracted with dichloromethane, and
the extract was dried over anhydrous sodium sulfate. After
the solvent was evaporated off under reduced pressure, the
residue was purified by column chromatography with toluene
as eluent to give 15.
4-(ter t-Bu tylth io)-3,6-diph en yl-1-(isopr opylth io)th ien o-
[3,4-c]th iop h en e (15): red crystals; yield 70%; mp 156-158
°C (acetonitrile); 1H NMR δ 0.92 (d, 6 H, J ) 6.7 Hz), 0.94 (s,
9 H), 2.54 (sep, 1 H, J ) 6.7 Hz), 7.33-7.46 (m, 6 H), 7.66-
7.74 (m, 4 H); IR (KBr) 1592, 1494, 1443 cm-1; UV (CH λmax
(nm) (log ꢀ) 516 (4.29), 294 (4.33), 249 (4.31). Anal. Calcd for
C25H26S4: C, 66.03; H, 5.76. Found: C, 66.30; H, 5.86.
Rea ction s of 2a ,b w ith NP M. To a solution of 2a ,b (0.2
mmol) in dry benzene (10 mL) was added NPM (0.2 mmol),
and the mixture was refluxed for 3 days under argon. After
the solvent was evaporated off under reduced pressure, the
residue was separated by column chromatography with toluene
as eluent to give the endo-cycloadducts 17a ,b and the exo-
cycloadducts 18a ,b.
1,4-Bis(ter t-b u t ylt h io)-3,6-d i(2-t h ien yl)t h ien o[3,4-c]-
th iop h en e (2b): purple crystals; yield 21%; mp 199-201 °C
dec (methanol); 1H NMR δ 1.06 (s, 18 H), 7.10-7.14 (m, 2 H),
7.33-7.36 (m, 2 H), 7.48-7.49 (m, 2 H); 13C NMR δ 30.12,
49.54, 111.12, 123.52, 126.35, 127.25, 129.90, 133.27, 147.57;
IR (KBr) 1458, 1362 cm-1; UV (hexane) λmax (nm) (log ꢀ) 538
(4.30), 297 (4.40), 245 (4.38). Anal. Calcd for C22H24S6: C,
54.96; H, 5.03. Found: C, 54.80; H, 5.16.
2,3,5,6-Tetr a p h en ylth ien o[3,2-b]th iop h en e (3):8 white
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crystals; yield 9%; mp 285-286 °C dec (CHCl3-hexane); H
NMR δ 7.24-7.28 (m, 8 H), 7.31-7.40 (m, 8 H), 7.46-7.49 (m,
4 H); 13C NMR δ 127.69, 128.56, 128.84, 129.10, 129.39, 134.64,
139.05, 139.10; IR (KBr) 1444 cm-1; UV (CH λmax (nm) (log ꢀ)
259 (4.26), 337 (4.41). Anal. Calcd for C30H20S2: C, 81.04; H,
4.53. Found: C, 80.78; H, 4.29.
En d o-cycloa d d u ct 17a : red crystals; yield 46%; mp 244-
1
246 °C dec (methanol); H NMR δ 1.08 (s, 9 H), 1.16 (s, 9 H),
4.53 (d, 1 H, J ) 8.5 Hz), 4.76 (d, 1 H, J ) 8.5 Hz), 6.88-6.92
(m, 2 H), 7.29-7.41 (m, 9 H), 7.66-7.67 (m, 2 H), 7.97-8.01
(m, 2 H); IR (KBr) 1709, 1492, 1385 cm-1; UV (CH2Cl2) λmax
Rea ction s of 2a ,b w ith TF A. To a solution of 2a ,b (0.2
mmol) in dry benzene (10 mL) was added TFA (0.6 mmol)
under argon, and the mixture was stirred at room temperature
for 20 h. After removal of the solvent under reduced pressure,
the residue was purified by column chromatography with
toluene as eluent to give 13a ,b.
(nm) (log ꢀ) 304 (4.00), 260 (4.21). Anal. Calcd for C36H35
-
NO2S4: C, 67.36; H, 5.50; N, 2.18. Found: C, 67.33; H, 5.43;
N, 1.94.
Exo-cycloa d d u ct 18a : red crystals; yield 35%; mp 240-
242.5 °C dec (methanol); 1H NMR δ 1.07 (s, 9 H), 1.12 (s, 9 H),
3.91 (d, 1 H, J ) 6.1 Hz), 4.25 (d, 1 H, J ) 6.7 Hz), 7.24-7.42
(m, 11 H), 7.53-7.57 (m, 2 H), 7.67-7.71 (m, 2 H); IR (KBr)
1711, 1495, 1371 cm-1; UV (CH2Cl2) λmax (nm) (log ꢀ) 303 (3.94),
259 (4.28). Anal. Calcd for C36H35NO2S4: C, 67.36; H, 5.50;
N, 2.18. Found: C, 67.10; H, 5.44; N, 1.96.
En d o-cycloa d d u ct 17b: pale yellow crystals; yield 69%;
mp 242.5-243 °C dec (methanol); 1H NMR δ 1.13 (s, 9 H), 1.24
(s, 9H), 4.50 (d, 1H, J ) 8.5 Hz), 4.65 (d, 1 H, J ) 9.1 Hz),
6.88-6.91 (m, 2H), 7.03-7.08 (m, 2 H), 7.27-7.36 (m, 5 H),
7.59-7.61 (m, 1 H), 7.84-7.85 (m, 1 H); IR (KBr) 1709, 1491,
1378 cm-1; UV (CH2Cl2) λmax (nm) (log ꢀ) 319 (4.06); MS m/ z
654 (M+). Anal. Calcd for C32H31NO2S6: C, 58.77; H, 4.78;
N, 2.14. Found: C, 58.79; H, 4.92; N, 1.90.
4-(ter t-Bu tylth io)-3,6-d ip h en ylth ien o[3,4-c]th iop h en e-
1(3H)-th ion e (13a ): red crystals; yield 97%; mp 132-133.5
1
°C (methanol); H NMR δ 1.20 (s, 9 H), 5.74 (s, 1 H), 7.28-
7.47 (m, 8 H), 7.68-7.71 (m, 2 H); IR (KBr) 1517, 1451 cm-1
;
UV (hexane) λmax (nm) (log ꢀ) 360 (4.11), 279 (4.27). Anal.
Calcd for C22H20S4: C, 64.04; H, 4.89. Found: C, 63.86; H,
4.78.
4-(t er t -B u t y lt h i o )-3,6-d i (2-t h i e n y l)t h i e n o [3,4-c ]-
th iop h en e-1(3H)-th ion e (13b): red crystals; yield 98%; mp
1
65-68 °C (methanol); H NMR δ 1.30 (s, 9 H), 6.06 (s, 1 H),
6.92-6.96 (m, 1 H), 7.08-7.11 (m, 2 H), 7.24-7.27 (m, 1 H),
7.44-7.46 (m, 1 H), 7.79-7.81 (m, 1 H); IR (KBr) 1519, 1448
cm-1; UV (CH2Cl2) λmax (nm) (log ꢀ) 371 (4.02), 293 (4.17); Anal.
Calcd for C18H16S6: C, 50.91; H, 3.80. Found: C, 50.65; H,
3.61.
Exo-cycloa d d u ct 18b: pale yellow crystals; yield 13%; mp
1
239-241 °C dec (methanol); H NMR δ 1.20 (s, 9 H), 1.22 (s,
Detection of 1,4-Bis(ter t-bu tylth io)-3,6-d ip h en yl-3H-
t h ien o[3,4-c]t h iop h en iu m Tr iflu or oa cet a t e (16a ). TFA
(0.06 mmol) was added to a solution of 2a (0.02 mmol) in
benzene-d6 (0.90 mL) containing TMS as an internal standard
9 H), 3.82 (d, 1 H, J ) 6.7 Hz), 4.07 (d, 1 H, J ) 6.7 Hz), 7.04-
7.11 (m, 2 H), 7.27-7.43 (m, 8 H), 7.62-7.64 (m, 1 H); IR (KBr)
1712, 1495, 1374 cm-1; UV (CH2Cl2) λmax (nm) (log ꢀ) 313 (4.08).
Anal. Calcd for C32H31NO2S6: C, 58.77; H, 4.74; N, 2.14.
Found: C, 59.05; H, 4.74; N, 1.91.
1
in a sample tube at room temperature, and then the H NMR