September 2014
EDOT Functionalizationed with TTF: Synthesis and Selective Esterification
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MS (EI): m/z = 260(M+, 100), 216, 186, 169. 3 and 30 were
difficult to separate and were used in the next reaction without
separation.
40ꢀC and stirred for 2 h; after the mixture cooled to RT, it was
allowed to react for another 10h. Then, the reaction mixture was
washed successively with saturated NaHCO3 and brine, dried over
MgSO4, and concentrated. The residue was purified by silica
column chromatography (CH2Cl2/n-hexane, 2:1, v/v) to give
Ester-1, a viscous oil (495mg, 68% yield). 1H-NMR (CDCl3,
500 MHz): d 6.34 (1H, d, J = 3.6 Hz, CH-thiophene), 6.33 (1H, d,
J = 3.6Hz, CH-thiophene), 4.41–4.31 (3H, m, —OCH2CH(CH2)
O—), 4.25 (1H, dd, cisJ = 2.2 Hz and gemJ = 11.7Hz, ═C(C)
OCH2), 4.06 (1H, dd, transJ = 7.5 Hz and gemJ = 11.7 Hz, ═C(C)
OCH2), 3.55 (2H, s, —SCH2COO—), 2.81 (4H, t, J = 6.8 Hz, —
SCH2CH2—), 2.43 (3H, s, —SCH3), 1.65–1.58 (4H, m, —CH2—),
1.43–1.36 (4H, m, —CH2—), 1.33–1.28 (8H, m, —CH2CH2CH3),
0.88 (6H, t, J=6.6Hz, —CH2CH3). 13C-NMR (CDCl3, 100 MHz)
d: 168.4, 141.1, 140.8, 134.7, 127.8, 127.6, 121.1, 112.4, 108.8,
108.6, 105.8, 100.2, 100.0, 71.1, 65.4, 63.4, 37.0, 31.3, 29.7, 28.2,
19.2, 14.0. MS (EI) = m/z 726 (M+, 100). HRMS (ESI) Calcd for
C28H38O4S9 requires (M+ + 1) 727.0335, Found 727.0331.
To a three-necked flask, 3 and 30 (2 g, 7.7 mmol), catalytic
amount of copper chromite, and quinoline (20 mL) were added
successively. The mixture was heated to 180ꢀC to form a
brown solution. The generated gas was absorbed with NaOH
solution through a gas tube. The reaction was carried out for
3 h, then cooled to RT, and filtrated; the filtrate was diluted
with ether (50 mL), washed with water (50 mL ꢁ 2) and brine,
and dried over MgSO4. The solvent was removed under
vacuum, and the residue was purified on silica column chro-
matography with CH2Cl2 : AcOEt = 1:1(v/v) as eluent to afford
4 and 40, a pale yellow liquid (1.02 g, 76% yield). GC–MS
(acetone) indicated: 4, RT 6.60 min; MS 172m/z = 172 (M+, 100),
127, 116, 45, 42. 40, RT 6.88; MS m/z = 172 (M+), 141, 116
(100), 57, 43. 4:40 = 6:1. They were used in the next reaction
without separation.
Ester-2.
The synthesis procedure was similar to that of
2-Methylthio-3-ethoxycarbonylthio-6,7-bis(hexylthio)
Ester-1, white cream solid (77% yield). MS (EI): m/z = 354 (M+,
100). The ratio of 60 to 6 was 2:9 obtained by HPLC (methanol/
water, 3:2, v/v).
tetrathiafulvalene (TTF-2).
To a stirred solution of TTF 1
(1.13 g, 2 mmol) in dried DMF (60 mL), CsOH.H2O (350 mg,
2.1 mmol) in absolute MeOH (5mL) was added over a period
of 30min under nitrogen. After stirring for 30min, ethyl
bromoacetate (0.55 mL, 5 mmol) was added, and the solution
turned its color from dark orange to yellow orange at once.
After stirring at RT for 5 h, the reaction mixture was distilled
under reduced pressure to remove excess ethyl bromoacetate as
well as the solvent. The residue was purified by column
chromatography on silica gel (CH2Cl2/petroleum ether, 2:3, v/v)
to give TTF 2 as reddish orange oil (1.12 g, 93% yield). 1H-NMR
(CDCl3, 500 MHz): d 4.21 (2H, q, J = 6.9 Hz, —OCH2CH3), 3.53
(2H, s, —SCH2COO—), 2.81 (4H, t, J = 7.2 Hz, —SCH2CH2—),
2.46 (3H, s, —SCH3), 1.68–1.58 (4H, m, —CH2—), 1.45–1.36
Ester-3.
The synthesis procedure was similar to that of
Ester-1, colorless oil (74% yield). MS (EI): m/z = 276 (M+,
100). The ratio of 70 to 7 was 1:6 obtained by HPLC (methanol/
water, 3:2, v/v).
Acknowledgments. This work was supported by National
Natural Science Foundation of China (No. 21076078, 20872035).
REFERENCES AND NOTES
(4H, m, —CH2—), 1.33–1.28 (11H, m, —OCH2CH3,
—
CH2CH2CH3), 0.89 (6H, t, J=6.6Hz, —CH2CH3). MS (EI) m/
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z= 600 (M+), 513, 482.
2-Methylthio-3-carboxythio-6,7-bis(hexylthio)tetrathia
fulvalene (TTF-3) (TTF-acid). To a stirred solution of TTF 2
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LiOH.H2O (420mg, 10mmol) in deionized H2O (5mL) was
added dropwise at RT. After stirring for 10h, 5M HCl (2 mL,
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stirred for another 30 min; diethyl ether (60mL) and water
(30 mL) were added, followed by adding 1M HCl till the pH
of water phase reached 2. The organic layer was decanted,
dried over MgSO4, and evaporated under reduced pressure to
afford a red solid (755 mg, 88% yield) that could be used in
the next step without further purification. The crude product
could be purified by column chromatography on silica gel
with CH2Cl2 as the eluent to remove the byproduct. The residue
was recrystallized with acetone to afford pure product, mp:
80–81ꢀC. 1H-NMR (CDCl3, 500 MHz): d 3.91 (2H, s), 2.85
(4H, t, J = 6.9 Hz), 2.50 (3H, s), 1.67–1.61 (4H, m), 1.43–1.38
(4H, m), 1.30–1.24 (8H, m), 0.88 (6H, t, J = 6.6 Hz). MS (EI)
m/z = 572 (M+) 513, 528, 482.
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Ester-1.
2-Methylthio-3-carboxythio-6,7-bis(hexylthio)
tetrathiafulvalene (TTF-3) (TTF-acid) (570 mg, 1 mmol) was
dissolved in freshly distilled CH2Cl2 (25 mL) under argon.
Dicyclohexylcarbodiimide (230 mg, 1.1 mmol), DMAP (123 mg,
1 mmol), and 1-hydroxybenzotriazole (135 mg, 1 mmol) were
added successively. After stirring for 30 min, 4 and 40 (0.3 g.
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet