Heteroatom rearrangements. Extension to aliphatic carboxylic acids

Abstract

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-anilino-2-cyano-3-(methylthio)acrylamide gives 3-phenylpyrimidin-4-ones (N,N double rearranged products) together with 1-phenylpyrimidin-4- ones (N,N double unrearranged products). In the case of 2-cyano-3-hydroxy-3-(methylthio)acrylamide, O,N double rearranged cyclic and chain compounds are produced. Furthermore, such rearrangements are observed in the reaction with carboxylic acid anhydrides in the presence of toluene-p-sulphonic acid.