Condensation reactions of benzils with ureas in ethylene glycol

초록

Reactions of benzils and urea in ethylene glycol at 180° for 1-2 hours gave 2,4,5-triaryloxazoles as major products and bicyclic imidazoimidazole-2,5-diones as minor products. N-Methylurea and W-phenylurea gave the oxazoles under similar conditions. The solvent seemed to assist the formation of oxazole by eliminating the isocyanate components as ethylene glycol biscarbamates.