Synthesis of polysubstituted 4,5,6,7-tetrahydrofuro[2,3-c]pyridines by a novel multicomponent reaction

A novel three-component synthesis of tetrahydrofuro[2,3-c]pyridines (1) from readily accessible starting materials is described. Simply heating a toluene solution of an aminopentynoate (2a), an aldehyde (3), and an alpha-isocyanoacetamide (4) in the presence of ammonium chloride provided the 4,5,6,7-tetrahydrofuro[2,3-c]pyridines (1) in good to excellent yield. The fused ring system is produced in this one-pot process by the concomitant formation of five chemical bonds.