Metal-Free Domino Synthesis of Novel Chromeno[2′,3′:4,5]Imidazo[1,2-a]Thienopyridines

Domino reaction of N-(cyanomethyl)thienopyridinium quaternary salts with o-hydroxybenzaldehydes leads to an effective formation of chromenes, annulated with imidazo[1,2-a]thienopyridine core. N-Cyanomethyl salts of all four isomeric thienopyridines—thieno[2,3-b]pyridinium, thieno[3,2-c]pyridinium, thieno[3,2-b]pyridinium, and thieno[2,3-c]pyridinium have been successfully used for the preparation of chromeno[2′,3′:4,5]imidazo[1,2-a]thienopyridines with moderate to good yields. © 2025 Elsevier B.V., All rights reserved.