Synthesis and microbial activity of new thiazolyl 1,4-benzothiazines

5-Acyl-2-aryl-4-methyl thiazoles 1 have been converted to 1-(2'-aryl-4'-met hylthiazol-5'-yl)-3-aryl-2propen-1-ones 2 by Claisen-Schmidt condensation. The chalcones 2 are brominated to give their bromo derivatives 3 which on h ydrolysis yield 1-(2'-aryl-4'-methylthiazol-5'-yl)-3-arylpropane-1,3-diones 4. The diones 4 when condensed with 2-aminobenzenethiol in refluxing DMSO furnish cyclic product, 2-aroyl-3-(2'-aryl-4'-methylthiazol-5'-yl)-4H-1 4-b enzothiazines 5. The results of microbial screening of the compounds 5 have been discussed.