Some Reactions of 2-Functionalized 3-Amino-4-aryl-6-(2′-thienyl)-thieno[2,3-b]pyridines: Synthesis of New Pyridothienopyrimidines, Pyridothienotriazines and Related Fused Tetracyclic Systems

Abstract

4-Aryl-3-cyano-6-(2'-thienyl)-pyridine-2(1 H )-thiones ( 2a-c ) were prepared and reacted with chloroacetonitrile or chloroacetamide to furnish 3-amino-4-aryl-6-(2'-thienyl)-thieno[2,3-b]pyridine-2-carbonitriles ( 4a-c ) and 2-carboxamide analogs 6a-c respectively. The reaction of 4a and 6a-c with a variety of reagents namely, formamide, carbon disulfide, phenyl isothiocyanate, ethylene diamine, sodium azide, triethyl orthoformate, and nitrous acid have been carried out and their products were identified. Most of these products were subjected to further reactions to obtain the rest of the title compounds.