Iminiumions derived from a condensation of glyoxal and N-methyl (R)-phenylglycinol react with allylic silanes (trimethylallyl and trimethylmethallylsilanes) and enoxysilanes (2-trimethylsilyloxypropene and 2-trimethylsilyloxystyrene). These reactions proceed in a totally stereoselective way as evidenced by a chemical correlation and an X-Ray analysis of a compound related to both series of experiments