O,N and N,N double rearrangement
Abstract
2-Cyano-3-hydroxy-3-(methylthio)acrylamide and 2-cyano-3-methylthio-3(phenylamino)acrylamide condenses with benzoic acid in the presence of polyphosphoric acid trimethylsilyl ester to give 5-cyano-4-methylthio-2-phenyl-1,3-oxazin-6-one (O,N double rearranged product) and 5-cyano-6-methylthio-2,3-diphenyl-1,3-diazin-4-one (N,N double rearranged product), respectively.