N-Bromosuccinimide as a Brominating Agent for the Transformation of N-H (or N-Benzyl) Ketoaziridines into Oxazoles

A novel procedure for the direct synthesis of 2,5-diaryloxazoles starting from N-H ketoaziridines is described. The method proceeds via the in situ formation of N-bromoketoaziridines in the presence of N-bromosuccinimide followed by the generation of intermediate azomethine ylides. A plausible mechanism for this transformation is proposed.