Ring transformation reactions starting from 6-imino-6H-1,3-thiazines

Ring transformation reactions of 6-imino-6H-1,3-thiazines (4), 6-imino-6H-1,3-thiazine hydroperchlorates (3), respectively, are initiated under basic conditions by a ring opening of the thiazine nucleous. Two possibilities exist, either intramolecular elimination occurs to give acrylonitriles (5), or addition of a nucleophile (YH) results in the formation of substituted acrylthio-amides (6). The way by which stable products were formed depends on both the functionality of the thiazine, and the reaction conditions. The way 4-->5 produce 1,3-benzoxazines (8), or 1,2,4-dithiazoles (14), respectively. The way 4 --> 6 gives pyrimidinethiones (7), or 1,2-dithioles (17), respectively. Upon treatment of thiazine perchlorates (3) with alkylhalides under basic conditions, acrylonitriles (18) are formed by the way 4 --> 5. Compounds (18) can be transformed to 1,2,4-triazoles (19).