7606
K. Rubina et al. / Tetrahedron 59 (2003) 7603–7607
parallel to furan ring being practically inaccessible. It
could explain the lower probability of thiolate anion
formation in the case of (E)-2-chlorovinyl(2-furfuryl)-
sulfide as we propose.
chromatography on silica gel using hexane/toluene or
hexane/ethyl acetate as eluent.
3.5. Transformation of (E)-2-chlorovinylsulfides in the
system Cs2CO3/18-crown-6/Pd(OAc)2/dppb
The substrate 1–4 (1 mmol) was added to the mixture of
Pd(OAc)2 (4.5 mg, 0.02 mmol) and 1,4-bis(diphenylphos-
phino)butane (dppb) (21.3 mg, 0.05 mmol) in dry toluene
(2 mL) under argon atmosphere. After five-minute stirring
Cs2CO3 (456 mg, 1.4 mmol) and 18-crown-6 (26 mg,
0.1 mmol) were added. The reaction mixture was stirred at
1108C up to substrate disappearance (GC control), filtered;
solvent was removed under reduced pressure. The crude
residue was purified on silica gel using hexane/toluene or
hexane/ethyl acetate as eluent.
3. Experimental
3.1. General
1H and 13C NMR spectra were recorded on a Varian Mercury
200 spectrometer at 200.06 and 50.31 MHz correspondingly
at 303 K. The chemical shifts are given relative to hexa-
methyldisiloxane (HDMSO, dH¼0.055) from solvent
(CDCl3) signal (dH¼7.25). Mass spectra were recorded on a
GC–MS HP 6890 (70 eV). GC analysis was performed on a
Chrom-5 instrument equipped with flame-ionization detector
using glass column packed with 5% OV-101/Chromosorb W-
HP (80–100 mesh) (1.2 m£3 mm).
3.5.1. (E)-1,4-Bis(phenylthio)-1-buten-3-yne (1c). Oil; Rf
0.5 (SiO2, hexane/toluene 10:1). MS, m/z (I, %): 268 (Mþ,
88), 235 (34), 234 (68), 202 (18), 191 (40), 190 (47), 158
(20), 147 (74), 121 (40), 115 (84), 114 (27), 102 (18), 89
(E)-2-Chlorovinylthio derivatives 1–4 were prepared
from corresponding thiols and ClCH2CHCl2 using solid
K2CO3 (then KOH)/18-crown-6/toluene or xylene as
described.13
1
(20), 77 (61), 69 (50), 51 (100), 39 (23). H NMR d ppm:
5.73 (d, 1H, J¼16 Hz, vCH), 6.94 (d, 1H, J¼16 Hz,
vCH), 7.15–7.46 (m, 10H, Ph). 13C NMR d ppm: 85.7
(uC), 95.8 (uC), 107.4 (vC), 125.3, 126.1, 126.4, 126.7,
128.1, 129.1, 131.5, 132.9, 139.8 (vC). Anal. calcd for
C16H12S2: C, 71.60; H, 4.51; S, 23.8. Found: C, 71.49; H,
4.56; S, 24.04.
3.2. Transformation of (E)-2-chlorovinylsulfides
by t-BuOK
To the solution of substrate 1–4 (1 mmol) in dry
toluene (2 mL) under argon atmosphere t-BuOK
(137 mg, 1.4 mmol) was added. The reaction mixture
was stirred at 1108C up to substrate disappearance (GC
control). Then the precipitate (KCl) was filtered off, and
toluene was evaporated under reduced pressure. The
crude residue was purified by column chromatography
on silica gel using hexane/toluene or hexane/ethyl
acetate as eluent.
3.5.2. (Z)-1,4-Bis(phenylthio)-1-buten-3-yne (1d). Oil, Rf
0.67 (SiO2, hexane/toluene 10:1). MS, m/z (I, %): 268 (Mþ,
70), 235 (35), 234 (55), 221 (10), 202 (12), 191 (31), 190 (45),
159 (15), 158 (20), 147 (60), 146 (20), 145 (37), 115 (83), 114
(26), 103 (14), 102 (16), 89 (20), 82 (32), 77 (63), 69 (52), 51
(100), 50 (28), 35 (35), 39 (24). 1H NMR d ppm: 5.80 (d, 1H,
J¼10 Hz, vCH), 6.75 (d, 1H, J¼10 Hz, vCH), 7.17–7.53
(m, 10H, Ph). 13C NMR d ppm: 83.9 (uC), 94.3 (uC), 105.9
(vC), 124.9, 126.1, 126.4, 127.5, 129.1, 129.2, 130.3, 134.4,
139.2 (vC). Anal. calcd for C16H12S2: C, 71.60; H, 4.51; S,
23.8. Found: C, 71.57; H, 4.50; S, 24.06.
3.3. Transformation of (E)-2-chlorovinylsulfides in the
system KOH/18-crown-6/Pd(OAc)2/dppb
3.5.3. (E)-1,4-(E)-Bis[(2-pyridyl)thio]ethene (2a). Oil, Rf
0.53 (SiO2, hexane/ethyl acetate 2:1). MS, m/z (I, %): 246
The substrate 1–4 (1 mmol) was added to the mixture of
Pd(OAc)2 (4.5 mg, 0.02 mmol) and 1,4-bis(diphenylphos-
phino)butane (dppb) (21.3 mg, 0.05 mmol) in dry toluene
(2 mL) under argon atmosphere. After five-minute stirring
KOH (78.4 mg, 1.4 mmol) and 18-crown-6 (26 mg,
0.1 mmol) were added. The reaction mixture was stirred at
1108C up to substrate disappearance (GC control), filtered;
solvent was removed under reduced pressure. The crude
residue was purified on silica gel using hexane/toluene or
hexane/ethyl acetate as eluent.
1
(Mþ, ,1), 136 (100), 78 (27), 067 (10), 51 (17). H NMR d
ppm: 7.04 (m, 2H, H-5, H-5 ), 7.21 (m, 4H, H-4, H-40,
CHvCH), 7.49–7.58 (m, 2H, H-3, H-30), 8.45 (m, 2H, H-6,
H-60). 13C NMR d ppm: 120.3 (vC), 121.7, 122.3, 136.5,
149.7, 157.6. Anal. calcd for C12H10N2S2: C, 58.51; H, 4.09;
N, 11.37; S, 26.03. Found: C, 58.64; H, 4.13; N, 11.40; S,
26.13.
3.5.4. (E)-1,2-Bis(2-furfurylthio)ethene (4a). Oil, Rf 0.54
(SiO2, hexane/ethyl acetate 10:1). MS, m/z (I, %): 252 (Mþ,
10), 81 (93), 53 (36). 1H NMR d ppm: 6.02 (s, 2H,
HCvCH), 6.20 (m, 2H, H-3, H-4), 7.29 (m, 1H, H-5). 13C
NMR d ppm: 11.9, 103.9 (CvC), 108.6, 111.2, 132.1. Anal.
calcd for C12H12O2S2: C, 57.11; H, 4.79; S, 25.41. Found:
C, 57.07; H, 4.74; S, 25.51.
3.4. Transformation of (E)-2-chlorovinylsulfides in the
system t-BuOK/Pd(OAc)2/dppb
The substrate 1–4 (1 mmol) was added to the mixture of
Pd(OAc)2 (4.5 mg, 0.02 mmol) and 1,4-bis(diphenylphos-
phino)butane (dppb) (21.3 mg, 0.05 mmol) in dry toluene
(2 mL) under argon atmosphere. After five-minute stirring
t-BuOK (137 mg, 1.4 mmol) was added. Reaction mixture
was stirred at 1108C up to substrate disappearance (GC
control), filtered; solvent was removed under reduced
pressure. The crude residue was purified by column
3.5.5. (E)-1,4-Bis(2-furfurylthio)-1-buten-3-yne (4c). Oil,
Rf 0.54 (SiO2, hexane/ethyl acetate 10:1). MS, m/z (I, %):
276 (Mþ, 100), 137 (45), 106 (15), 94 (12), 78 (10), 65 (15),
1
51 (18), 43 (10). H NMR d ppm: 6.11 (d, 1H, J¼13 Hz,