Synthesis of 2-methylthio-4H-1,3-thiazines

2-Methylthio-4H-1,3-thiazines or their mixtures with 5-alkylidene-4H-5,6-dihydro-1,3-thiazines were obtained by cyclization of methyl N-3-oxoalkyldithiocarbamates in sulfuric acid. The regiospecificity of the reaction is determined by the structures of the starting compounds. The structures of the synthesized thiazines were confirmed by spectral methods of analysis (IR and ¹H and ¹³C spectroscopy).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 991–993, July, 1992.