Cascade synthesis of thieno[2,3-b]pyridines by using intramolecular cyclization reactions of 3-cyano-2-(organylmethylthio)pyridines

Abstract

2-Amino-4-aryl-6-mercaptopyridine-3,5-dicarbonitriles as starting materials have been prepared by reducing of 2-amino-4-aryl-6-(phenylthio)pyridine-3,5-dicarbonitrile derivatives which were synthesized on stepwise one-pot three component reaction of malononitrile, aldehydes and thiophenol in the presence of base catalysts such as triethylamine, high surface area (HSA) MgO or nanocrystalline magnesium oxide. Alkylation of 2-amino-4-aryl-6-mercaptopyridine-3,5-dicarbonitriles with α-halogen compounds in presence of sodium alkoxide as base catalyst followed with cyclization afforded the thieno[2,3-b]pyridine derivatives in excellent yields and in a short reaction time.