vinylsilanes by the reaction with iodosylbenzene and triethyloxonium tetrafluoroborate. The reaction occurs stereospecifically with retention of configuration. Vinyliodonium salts are highly effective as the activated species of vinyl iodides. Thus, a variety of substituted olefins including α-cyano and α-nitro olefins, vinyl sulfides, vinylhalides, and α,β-unsaturated esters, were prepared from under mild