Metal‐Free Domino Synthesis of Novel Chromeno[2′,3′:4,5]Imidazo[1,2‐ <i>a</i> ]Thienopyridines

ABSTRACT 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.