Novel synthesis of 3-amino-4-oxo-(2H)-pyrazolo[3′,4′:4,5]pyrimido-[2,1-b] benzothiazole and its 2- and 3-substituted derivatives

Article abstract of DOI:10.1002/jhet.5570400322

Reaction of 4H-pyrimido[2,1-b]benzothiazole-2-thiomethyl-3-cyano-4-one (1) with hydrazine hydrate/aryl hydrazine/heteryl hydrazine in the presence of anhydrous potassium carbonate and dimethyl formamide afforded 3-amino-4-oxo-(2H)/aryl/heteryl pyrazolo[3′,4′:4,5]pyrimido[2,1-b]benzothiazoles in good yield. These pyrazole derivatives on diazotization followed by replacement with hydroxy, chloro, bromo, iodo and on reduction gave the corresponding 3-substituted derivatives.