Synthesis of 3-alkyl-5-phenylmethylidene-2-thio-4-imidazo- lidinones

α-Azidoacetic ester, obtained from nucleophilic substitution reaction of chloroacetic ester and sodium az-ide,and benzaldehyde were condensed into α-azidophenyl-methylideneacetic ester. α-Ethoxycarbonylphenylmethyli-deneiminophosphoranes, prepared from Staudinger reaction of α-azidophenylmethylideneacetic ester and tripheny-Iphosphine,reacted with alkyl isocyanate and Na2S/HOAc via aza-Wittig reactions in series with three components to give 3-alkyl-5-phenylmethylidene-2-thio-4-imidazolidino-nes. The reaction condition and the spectral properties of cyclized compounds were researched and a possible mechanism for the cyclization reaction was put forward. All the cyclized products are new, and their structures were confirmed by elemental analysis, IR, HNMR and MS.