The reaction of methyl 2-bromo-6-(trifluoromethyl)-3-pyridinecarboxylate (1) with methanesulfonamide gave methyl 2-[(methylsulfonyl)amino]-6-(trifluoromethyl)-3-pyridine-carboxylate (2). Alkylation of compound 2 with methyl iodide followed by cyclization of the resulting methyl 2-[methyl(methylsulfonyl)amino] -6-(trifluoromethyl)-3-pyridinecarboxylate (3) yielded 1-methyl-7-(trifluoromethyl)-1 H-pyrido[2,3-c] [1,2] thiazin-4(3 H)-one 2,2-dioxide (4). The reaction of compound 4 with alpha,2,4-trichlorotoluene, methyl bromopropionate, methyl iodide, 3-trifluoromethylphenyl isocyanate, phenyl isocyanate and 2,4-dichloro-5-(2-propynyloxy)phenyl isothiocyanate gave, respectively, 4-[(2, 4-dichlorophenyl)methoxy]-1-methyl-7-(trifluoromethyl)-l H-pyrido[2,3-c][1, 2] thiazine 2,2-dioxide (5), methyl 2-[[1 -methyl-2,2-dioxido-7-(trifluoromethyl)-1 H-pyrido[2,3-c][1,2]thiazin-4-yl]oxy]propanoate (6), 1,3,3-trimethyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4(3H)-one 2,2-dioxide (7), 4-hydroxy-1-methyl-7-(trifluoromethyl)-N-[3-(trifluoromethyl)phenyl]-1 H- pyrido[2,3-c][1,2]thiazine-3-carboxamide 2,2-dioxide (8), 4-hydroxy-1-methyl-7-(trifluoromethyl)-N- phenyl-1 H-pyrido[2,3-c][1,2]thiazine-3-carboxamide 2,2-dioxide (9) and N-[2,4-dichloro-5-(2- propynyloxy)phenyl]-4-hydroxy-1-methyl-7-(trifluoromethyl)-1 H-pyrido[2,3-c][1,2]thiazine-3-carboxamide 2,2-dioxide (10).
