F. Blockhuys et al. / Journal of Molecular Structure 485–486 (1999) 87–96
95
25; v/v) as the mobile phase. NP-HPLC analyses were
performed on an Alltech AdsorboSphere᭨ SI column,
particle size 10 mm, i.d. 4.6 mm, length 250 mm with
different mobile phases depending on the analyte.
Chemical shifts d are in ppm with respect to TMS.
added. The temperature is raised to room temperature
and the mixture is stirred for 30 min. The reaction
mixture is then poured into a mixture of 100 ml of
36% HCl and 850 ml of water and vigorously stirred.
Using a saturated NaHCO3 solution the pH is raised to
6. The water phase is separated and washed 7 times
with ether. The combined organic phases are dried,
the solvent is evaporated and the resulting solids puri-
fied by sublimation at 50ЊC/0.2 mmHg, yielding 3.0 g
5.1. E-1,2-bis(3-methoxy-2-thienyl)ethene (3), BMTE
An amount (27.5 ml) of 1.6 M BuLi solution in
hexane (0.044 mol) was added dropwise to a solution
of 5 g of 3-methoxythiofeen (0.044 mol) in 100 ml
freshly dried diethyl ether and the resulting mixture
is stirred for 2 h. Meanwhile, 1.07 g of Mg metal
(0.044 mol) and 3.8 ml of 1,2-dibromoethane
(0.044 mol) are mixed in 40 ml of ether and this
mixture is refluxed until the metal is completely
dissolved. The second mixture is then added at once
to the first and the new mixture is stirred for 1 h. To
the resulting Grignard reagent are added consecu-
tively 450 mg of NiCl2(dppp) (0.830 mmol), 2 ml of
E-1,2-dichloroethene (0.022 mol) and 50 ml of
diethyl ether. The temperature is raised to 30ЊC and
kept at 30ЊC during the night. The organic phase is
washed thrice with 50 ml of water, the solvent is
evaporated, the residue precipitated in hexane, filtered
and dried; the yield is 3.4 g (61%). M.p. 121–
123ЊC. UV–Vis (EtOEt): lmax 361 nm (log e
4.3). 1H NMR (CDCl3): CH3O–(3.90; s), –CHy
(6.95; s), H(5) (7.00; d;5.5 Hz), H(4) (6.79; d;
5.5 Hz). 13C NMR (CDCl3): CH3O– (58.8), –CHy
(116.1), C(2) (120.9), C(3) (154.7), C(4) (116.8),
C(5) (121.5).
1
(0.021 mol; 48%) of product. M.p. 84ЊC. H NMR
(CDCl3): CH3O–(3.90; s), –CHO (9.90; d; 1.2 Hz), a-
H (7.64; dd; 1.2 and 5.5 Hz), b-H (6.88; d; 5.5 Hz).
13C NMR (CDCl3): CH3O–(58.9), –CHO (181.1),
ring-C2 (115.9), ring-C3 (165.1), ring-C4 (121.4),
ring-C5 (135.0).
5.4. E-1-cyano-1-(2-thienyl)-2-(3-methoxy-2-
thienyl)ethene (7), CTMTE
One gram of 3-methoxy-2-thiophenealdehyde
(0.007 mol) (5) and 0.9 g of 2-thienylacetonitrile
(0.007 mol) (6) are dissolved in 20 ml of freshly
dried ethanol. In a separate vessel 0.2 g of Na metal
(0.009 mol) is dissolved in 15 ml of dry ethanol and
this solution is added dropwise to the former; a yellow
precipitate is immediately formed. The solvent is
boiled for an instant and then immediately cooled.
The resulting precipitate is filtered off and the filtrate
is kept and yields another precipitate. CTMTE is puri-
fied by sublimation first at 50ЊC/0.2 mmHg, to remove
the aldehyde (5), and then at 110ЊC/0.1 mmHg to
isolate CTMTE (7); the yield is 0.9 g (52%). M.p.
110–112ЊC. UV–Vis (CH3OH): lmax(E) 381 nm
(log e 4.5), lmax(Z) 345 nm (log e 4.3). MS
(ES): m/z 248 [MHϩ], 233[MH ϩ –CH3], 221, 216,
172, 97 [C5H5S ϩ ] (base peak). IR (KBr): n
1239 cmϪ1[n (COC)], 1435, 1462, 1511, 1527[g(thio-
phene ring)], 1580[n(CyC)], 2208[n(CxN)],
2855[n(CH3)], 3020[n(–CHy)], 3107[n(CH)(thio-
5.2. Z-1,2-bis(3-methoxy-2-thienyl)ethene
The Z-form of BMTE was synthesized by adding
2 ml of Z-1,2-dichloroethene (0.022 mol) in the final
step, but could not be isolated.
5.3. 3-methoxy-2-thiophenealdehyde (5)
1
phene ring)]. H NMR ((CD3)2CO): E: CH3O–(4.04;
At room temperature, 38 ml of a 1.6 M BuLi solu-
tion in hexane is added to a mixture of 6.2 g of
TMEDA
(0.053 mol) and 5 g of 3-methoxythiophene
(0.044 mol) in 30 ml of dry hexane. After refluxing
for 30 min, 60 ml of dry THF are added and the
resulting mixture is cooled to Ϫ 40ЊC. During a
period of 10 min, 6 ml of DMF (0.078 mol) are
s), –CHy (7.71;d;0.5 Hz), H(4A) (7.14; d; 5.6 Hz),
H(5A) (7.76; dd; 5.6 and 0.5 Hz), H(3B) (7.28; dd;
3.7 and 1.2 Hz), H(4B) (7.12; dd; 5.1 and 3.7 Hz),
H(5B) (7.48; dd; 5.1 and 1.2 Hz); Z: CH3O–(4.00;
s), –CHy (7.66; d; Hz), H(4A) (7.02;d;5.6 Hz),
H(5A) (7.74; dd; 5.6 and 0.5 Hz), H(3B) (7.26; dd;
3.7 and 1.2 Hz), H(4B) (7.19; dd; 5.1 and 3.7 Hz),
H(5B) (7.58; dd; 5.1 and 1.2 Hz). 13C NMR
(N,N,N0,N0-tetramethylethylenediamine)