反应详情

To a solution of triphenyl(2,3,6-trifluorobenzyl)phosphonium bromide (428 mg, 0.88 mmol) in THF at 0° C. was added potassium tert-butoxide (99 mg, 0.88 mmol). After the reaction was stirred for 1 h, it was warmed to room temperature and a solution of ethyl 1-(4-fluorophenyl)-2-formyl-1H-imidazole-5-carboxylate (16) (210 mg, 0.80) in THF (1 mL) was added. The mixture was refluxed for 6 h, cooled to room temperature, filtered, and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel (0-40% EtOAc in hexanes, Rf=0.2 in 80/20 hexanes/ethyl acetate) to yield (E)-ethyl 1-(4-fluorophenyl)-2-(2,3,6-trifluorostyryl)-1H-imidazole-5-carboxylate (17) as the only stereoisomer.

1. temperatureThe mixture was refluxed for 6 h
2. temperaturecooled to room temperature
3. filtrationfiltered
4. concentrationconcentrated in vacuo
5. customThe residue was purified by flash column chromatography on silica gel (0-40% EtOAc in hexanes, Rf=0.2 in 80/20 hexanes/ethyl acetate)