[Pyrazolo[3,4d][1,3]thiazine systems]

The synthesis of 1,2,4,6-tetrahydro-2-methyl-3-hydroxypyrazolo [3,4-d] [1,3]thiazine-4,6-dithione is described. By spectroscopic methods the anphionic structure of this and other related compounds is demonstrated. In addition, the action of alkylating reagents upon pyrazolo-[3,4-d] [1,3]thiazine-4,6-dithionic compounds is examined and described. The biological activity of the new synthesized compounds is reported.