Novel synthesis and biological activity of 2‐substituted derivatives of 3‐cyano‐4‐imino‐2‐methylthio‐8‐methoxy‐4<i>H</i>‐pyrimido[2,1‐<i>b</i>][1,3]benzothiazole and 3‐amino‐4‐imino‐8‐methoxy‐2<i>H</i><b>‐</b>pyrazolo[3′,4′:4,5]pyrimido[2,1‐<i>b</i>][1,3]benzothiazole

Abstract

Abstract 2‐Amino‐6‐methoxybenzothiazole 1 on reaction with bis(methylthio)methylene malononitrile 2 in the presence of dimethyl formamide and catalytic amount of anhydrous potassium carbonate afforded 3‐cyano‐4‐imino‐8‐methoxy‐4 H ‐pyrimido[2,1‐ b ][1,3]benzothiazole 3 . Under similar experimental conditions, compound 3 on treatment independently with arylamines/heterylamines/phenols/compounds containing active methylene group yielded corresponding 2‐substituted derivatives of compound 3 ( 4a , 4b , 4c , 4d , 5a , 5b , 5c , 6a , 6b , 6c , 6d , 6e , and 7a , 7b , 7c , 7d , 7e ). Similarly, novel heterocyclic compounds, 3‐amino‐4‐imino‐8‐methoxy‐2 H 8a /aryl 8b – c /heteryl 8d , 8e , 8f /pyrazolo[3′,4′:4,5]pyrimido[2,1‐ b ][1,3]benzothiazoles, were prepared by heating compound 3 independently with hydrazine hydrate/arylhydrazines/heterylhydrazines, respectively. All these newly synthesized compounds were screened for antimicrobial activity. J. Heterocyclic Chem., (2011).