Chemistry Reference
In-Depth Information
Br
HS
S
S
S
NBS
n
-BuLi
"S"
CuO
S
S
S
245
Br
Br
Br
330
331
332
Scheme 83 Synthesis of 245 [
131
]
S
S
Br
Br
1) 2eq.
n
-BuLi
2) CuCl
2
Br
S
S
S
333
313
246
S
29%
94%
S
Br
334
Scheme 84 Synthesis of 246 [
95
]
Various other DTTs with extended conjugation have been reported, for example
Scheme
81
shows how aldehydes 325 [
129
], themselves prepared by alternative
routes, were used to prepared ethene-linked 326. Schemes
81
and
82
illustrate the
use of cross-couplings to add aryl units [
130
].
3.4 Dithieno[2,3-b;2
0
,3
0
-d]thiophene (245)
A three-step synthesis of the DTT dithieno[2,3-
b
;2
0
,3
0
-
d
]thiophene (245), started
from 3-bromo-2-(thien-3-yl)thiophene (330) utilized bromination to 331, then
treatment with
n
-BuLi and finally elemental sulfur producing 332; heating this
thiol with CuO gave 245 (Scheme
83
)[
131
].
3.5 Dithieno[3,4-b;3
0
,2
0
-d]thiophene (246)
The synthesis of DTT dithieno[3,4-
b
;3
0
,2
0
-
d
]thiophene (246) starts with the reaction
of 3-bromo-2-lithiothiophene (313) with disulfide 333 to give 334. Dilithiation with
n
-BuLi and then oxidative ring closure using CuCl
2
lead to 246 [
95
] (Scheme
84
).
DTT (246) has been electropolymerized [
103
,
132
].
3.6 Dithieno[3,4-
b
;2
0
,3
0
-
d
]thiophene (247)
3-Lithiothiophene reacted with disulfide 335 gave 336. Next, regioselective
bromination produced dibromide 337, reaction of which with two equivalents of
