In the course of the syntheses of 1, 3-thiazines and related compounds, we found an interesting condensation reaction which involved a novel rearrangement. Thus, 2-cyano-3- mercapto-3-(methylthio) acrylamide (1) reacted with benzoic acid in the presence of polyphosphate ester (PPEY to give 5-carbamoyl-4-(methylthio)-2-phenyl-1, 3-thiazin-6-one (9). 3 The structures of 9 and its 2, 3-dihydro derivative 10 were unequivocally determined ...
