α-Methylene-β-amino Ketone Derivatives from β-Ketoallylsilanes

β-Ketoallylsilanes are synthesized by the Horner−Emmons reaction starting from novel silylated ketophosphonates and various aldehydes. The reactions of β-ketoallylsilanes with NsONHCO₂Et and CaO produce α-methylene-N-(ethoxycarbonyl)-β-amino ketones through the ring opening of the intermediate aziridine, which is favored by the presence of the trimethylsilyl group. With chiral β-ketoallylsilanes we obtained a stereoselective amination reaction with a 90% diastereomeric excess. α-Methylene-N-(ethoxycarbonyl)-β-amino ketones are isolated in 39−60% yields and characterized.