Ammonium Chloride → 3-(4-Bromo-thiophen-2-yl)-acrylonitrile

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Reaction Conditions

Reaction Steps

A solution of diethyl(cyanomethyl)phosphonate (2.1 mL, 12.9 mmol) in anhydrous THF (50 mL) was cooled to 0° C. under nitrogen and treated with KN(TMS)2 (11 mmol of a 0.5 M solution in toluene). After stirring for 15 min at 0° C., a solution of 4-bromo-2-thiophenecarboxaldehyde 63 (Aldrich, Wis.) (1.9 g, 10 mmol) in anhydrous THF (50 mL) was added and the resulting mixture was stirred for 30 min at 0° C. Saturated aqueous NH4Cl solution was added and the crude product extracted three times with diethylether. The ether extracts were dried over Na2SO4, filtered, and evaporated, and the product was purified by flash chromatography on a silica gel column (eluent: 5% EtOAc in hexane). The major fractions were combined and concentrated to give 76 (2.1 g) in 9.3 to 1 ratio of trans to cis isomers as a white solid; For trans isomer: 1H NMR (400 MHz, d6-DMSO) δ: 7.90 (s, 1H), 7.77 (d, J=16.5 Hz, 1H), 7.57 (s, 1H), 6.28 (d, J=16.5 Hz, 1H); For cis isomer: 1H NMR (400 MHz, d6-DMSO) δ 7.97 (s, 1H), 7.65 (s, 1H), 7.57 (d, J=11.1 Hz, 1H), 5.82 (d, J=11.7 Hz, 1H). MS (EI) m/z [(M+H+) (79Br)] 214 and [(M+H+) (81Br)] 216.

Provenance & Evidence