The addition of ethoxycarbonylnitrene, generated from ethyl N-(p-nitrobenzenesulphonyloxy)carbamate under liquid-liquid phase-transferconditions to vinyl-, α-bromovinyl- and (β-methoxycarbonylvinyl)(trialkyl)silanes affords the corresponding 1-ethoxycarbonyl-2-trialkylsilylaziridines.