Regioselective one-pot synthesis of 5-CHLORO-3-METHYL8-TRIFLUOROMETHYL-4H- l,4-BENZOTHIAZINES

Abstract

5-Chloro-3-methyl-8-trifluoromethyl-4H-l, 4-benzothiazines have been synthesized by an efficient synthetic method in a single step involving heterocyclization of 2amino-3-chloro-6-trifluoromethylbenzenethiol with D-ketoesters or D-diketones. 2Amino-3-chloro-6-trifluoromethylbenzenethiol was prepared by hydrolytic cleavage of 2-amino-4-chloro-7- trifluoromethylbenzothiazole which in turn was prepared by brominative cyclization of 2-chloro-5-trifluoromethylphenylthiourea. The phenylthiourea was prepared by the reaction of 2-chloro-5-trifluoromethylaniline with ammonium thiocyantate. The structures of the synthesized 4H-1,4-benzothiazines have been characterized by their elemental analyses and spectral characteristics.