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Paper | Regular issue | Vol 60, No. 10, 2003, pp.2273-2286
Published online, 1st September, 2003
DOI: 10.3987/COM-03-9852
■ Ring Transformation Reactions Starting from 6-Imino-6H-1,3-thiazines

Detlef Briel

*Institut für Pharmazie, -Pharmazeutische Chemie-, der Universität Leipzig, Brüderstr. 34, D-04103 Leipzig, Germany

Abstract

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 acrylthioamides (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).