Synthesis of Substituted Pyrano[3,4‐b]Quinolines by Silver‐Catalyzed Regioselective Intramolecular Cyclization of 3‐Alkynylquinoline Aldehydes

A novel approach for the synthesis of regioselective pyrano[3,4‐b]quinolines from 3‐alkynylquinoline aldehydes with alcohols as nucleophiles has been elucidated. This protocol has shown high generality of functional group and provides the pyrano‐annulated products good to excellent yields. This methodology was adopted a new synthetic strategy to develop the 3‐alkynylquinolinealdehydes by using methanol as a C1 source.