Synthesis of 7-Bromo/5,6-Dimethyl-4 H -1,4-Benzothiazines and Their Conversion into Sulfones

The synthesis of 7-bromo/5,6-dimethyl-4 H -1,4-benzothiazines and their conversion into sulfones is reported. The 7-bromo/5,6-dimethyl-4 H -1,4-benzothiazines were synthesized by the condensation and oxidative cyclization of 2-amino-5-bromo/3,4-dimethylbenzenethiol with g -diketones in dimethyl sulfoxide. The reaction is believed to proceed via an enaminoketone system. 4 H -1,4-Benzothiazine sulfones have been synthesized by the oxidation of 4 H -1,4-benzothiazines using 30% H 2 O 2 in glacial acetic acid. The structures of all newly synthesized compounds have been confirmed by elemental analysis and spectral studies.