Preparation of (5-Bromobenzofuro)[3, 2-d ]-3, 1-oxazine Derivatives

Abstract

Treatment of 2-acetylbenzo[b]furan-3-alkylcarboxamides with DMF-POCl₃ complex in dry DMF gave novel products having exo-formylmethylene group. Structure of the products was identified as (E or Z )-4-(formylmethylene)-2-(E)-(2-phenylvinyl)-(5-bromobenzofuro)[3, 2-d]-3, 1-oxazine by ¹H-NMR,¹³C-NMR and MS. Tentative mechanism of the new ring closure reactions was proposed. These compounds suggested that new ring closure reactions was found under the Vilsmeier conditions.