New syntheses of some 1,3-oxazine derivatives

Abstract

2,3-Dihydro-6-methyl-1,3-oxazine-2,4-dione has been prepared from NN-dimethylurea with either diketen or ethyl acetoacetate and the analogous 6-phenyl oxazine derivative from NN-dimethylurea and ethyl benzoyl acetate in acetic acid–acetic anhydride solution; structures of the oxazines were confirmed by ¹³C n.m.r. spectra and by subsequent conversion with ammonia or amines into substituted uracils.