Stereoselective C(2)-Vinylation of 1-Substituted Imidazoles with 3-Phenyl-2-propynenitrile

摘要

First examples of direct vinylation of 1-substituted imidazoles at the 2-position of the imidazole nucleus are described. 1-Substituted imidazoles la-e are C(2)-vinylated with 3-phenyl-2-propynenitrile (2) at room temperature without catalyst and solvent to afford 3-(1-organyl-1H-imidazol-2-yl)-3-phenyl-2-propenenitriles 3a-e, mainly (c.a. 95%) as (Z)-isomers, in 56-88% yield. The reaction is likely to involve the zwitterionic intermediates, which prototropically isomerizes to imidazole carbene and eventually undergoes the selective 3,2-shift of the functionalized vinyl substituent.