Chloroform → 3-Cyano-2-(4-nitrophenylthio)-5-[2-(4-ethoxycarbonylphenyl)ethenyl]pyridine

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A mixture of 4.544 g (7.42 mmol) of [3-cyano-2-(4-nitrophenylthio)-5-pyridinylmethyl]triphenylphosphonium bromide, 0.751 g (7.42 mmol) of triethylamine and 50 mL of chloroform was stirred at room temperature for 15 minutes and 1.322 g (7.42 mmol) of 4-ethoxycarbonylbenzaldehyde then were added. After stirring at room temperature for 96 hours, 100 mL of water were added, the mixture was filtered, and the organic layer was separated and washed twice with 100 mL portions of water, dried and filtered. Evaporation of the filtrate under reduced pressure gave a residue which was chromatographed on silica gel. Unreacted aldehyde was eluted with 2:1 petroleum ether:benzene, while the title compound, alternatively named as 2-(4-nitrophenylthio)-3-cyano-5-(4-ethoxycarbonylstyryl)pyridine, was eluted with benzene. Evaporation of the benzene eluate gave 2.82 g (88%) of 3-cyano-2-(4-nitrophenylthio)-5-[2-(4-ethoxycarbonylphenyl)ethenyl]pyridine as a light yellow solid. The product turns from a solid to a gum below 100° C. and then to a clear liquid between 180 and 220° C.; NMR (Me2SO-d6) delta 1.34 (t, 3H, J=6.3 Hz), 4.32 (g, 2H, J=6.3 Hz), 6.73 (d, 1H, J=13 Hz), 6.99 (d, 1H, J=13 Hz), 7.27 (d, 2H, J=9 Hz), 7.74, 7.85, 7.94 (dd, 2H, 2H), 8.26, 8.31 (dd, 2H, 1H), 8.38 (d, 1H, J=1.8 Hz); IR (KBr) 2220, 1707, 1605, 1597, 1575, 1512, 1344, 1295-1277, 1174 cm31 1.

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