Heteroatom Rearrangements. Extension to Aliphatic Carboxylic Acids
2-Cyano-3-mercapto-3-(methylthio)acrylamide condenses with aliphatic carboxylic acids in the presence of polyphosphoric acid trimethylsilyl ester to give the corresponding 1,3-thiazin-4-ones (S,N double unrearranged products); under the same conditions, 3