L. Grimaud et al. / Tetrahedron Letters 43 (2002) 7477–7479
7479
treated with a solution of 630 mL of DBU (3.9 mmol,
1.1 equiv.) in 10 mL of THF at 20°C. The resulting
solution was stirred for 45 min at 20°C and quenched
with 20 mL of saturated aqueous NH4Cl. The aqueous
phase was extracted with 3×20 mL of Et2O. The com-
bined organic layers were washed with brine, dried over
anhydrous MgSO4, filtered and concentrated in vacuo
to give without further purification 941 mg (100%) of
mixture was stirred for 1.5 h at 20°C, and the layers
were separated. The aqueous phase was extracted with
3×40 mL of Et2O. The combined organic layers were
washed with brine, dried over anhydrous MgSO4,
filtered and concentrated in vacuo. The resulting yellow
oil was purified by flash chromatography on silica gel
(ether/petroleum ether 60:40) to give 576 mg (87%) of
10b as white crystals: mp 43–44°C; 1H NMR (400 MHz,
CDCl3) l 7.79 (d, J=8.2 Hz, 2H), 7.35–7.25 (m, 7H),
4.58 (d, J=11.2 Hz, 1H), 4.37–4.32 (m, 1H), 4.35 (d,
J=11.2 Hz, 1H), 3.95 (s, 1H), 3.52–3.48 (m, 1H), 3.30
(dd, J=14.3, 7.7 Hz, 1H), 3.20 (dd, J=14.3, 3.8 Hz,
1H), 2.44 (s, 3H), 2.11–2.06 (m, 1H), 1.75–1.65 (m, 2H),
0.90, 0.88 (2d, J=6.6 Hz, J=6.8 Hz, 6H); 13C NMR
(100 MHz, CDCl3) l 144.7, 137.9, 136.8, 129.8, 128.3,
127.9, 127.6, 82.4, 71.0, 65.5, 62.5, 35.6, 29.4, 21.5, 18.2,
16.3; IR (KBr) 3503 (br), 3030, 2960, 2872, 1598, 1496,
1454, 1388, 1301, 1139, 1087, 1068, 1028 cm−1; MS
1
the substituted (E)-vinylsulfone 8b as a brown oil: H
NMR (200 MHz, CDCl3) l 7.81–7.73 (m, 2H), 7.33–
7.22 (m, 2H), 7.02 (dt, J=15.0, 7.2 Hz, 1H), 6.41 (dt,
J=15.0, 1.4 Hz, 1H), 3.55–3.35 (m, 1H), 2.40 (s, 3H),
2.40–2.20 (m, 2H), 1.74–1.58 (m, 1H), 0.92, 0.91 (2d,
J=6.8 Hz, 6H); 13C NMR (50 MHz, CDCl3) l 144.1,
143.6, 137.7, 132.6, 129.8, 127.6, 74.7, 36.2, 33.6, 21.5,
18.5, 17.2; IR (thin film) 3519, 3047, 2960, 2874, 1666,
1633, 1597, 1495, 1469, 1316, 1144 cm−1; Anal. calcd for
C14H20O3S: C, 62.65; H, 6.51. Found: C, 62.71; H, 7.62.
(GC, CI NH3) m/z 394 (M+NH4 ), 377 (M+H+), 359,
+
269, 188; Anal. calcd for C21H28O4S: C, 66.99; H, 7.50.
Found: C, 66.95; H, 7.59.
To a solution of 240 mg (0.90 mmol) of vinylsulfone 8b
in 5 mL of THF at 0°C was added 105 mL (1.0 mmol,
1.1 equiv.) of freshly distilled benzaldehyde, followed
by 10 mg (0.1 mmol, 0.1 equiv.) of t-BuOK, and the
resulting solution was stirred for 15 min at 0°C. This
sequence (addition/stirring) was repeated twice, and the
reaction mixture was quenched with 30 mL of saturated
aqueous NH4Cl. The aqueous phase was extracted with
3×30 mL of Et2O. The combined organic layers were
washed with brine, dried over anhydrous MgSO4,
Acknowledgements
The CNRS and the Ecole Polytechnique are thanked
for financial support.
1
filtered and concentrated in vacuo. Analysis of the H
References
NMR of the unpurified product showed a >95:5 ratio
of diastereomers. The resulting yellow solid was recrys-
tallized from ethyl acetate/petroleum ether (1:3) to give
267 mg (80%) of 9b as a cotton-like white solid: mp
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1
139–140°C; H NMR (400 MHz, CDCl3) l 7.81–7.77
(m, 2H), 7.28–7.10 (m, 7H), 5.41 (s, 1H), 4.50–4.37 (m,
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