Synthesis and some novel reactions of 8-chloro-2H-[1,2,4]triazino[3,4-b] [1,3]benzothiazole-3,4-dione and 6-chloro-2-hydrazino-1,3-benzothiazole

3,8-Dichloro-4H-[1,2,4]triazino[3,4-b][1,3]benzothiazole-4-one on reaction independently with sodium hydroxide solution and sodium azide undergo novel ring contraction reactions to give 7-chloro[1,2,4]triazolo[3,4-b][1,3] benzothiazole and 8-chloro tetrazolo[1′,5′:1,5][1,2,4]triazolo[3,4-b][1,3]benzothiazole respectively.