Cu(I)-Catalyzed Oxygen and Nitrogen Nucleophiles Triggered Regioselective Synthesis of Furo/Pyrrolo-Annulated Quinolines.

Cu(I)-catalyzed intramolecular annulation of o-ethynylquinoline-3-carbaldehydes leads to the synthesis of alkoxy/imidazole-substituted 1,3-dihydrofuro[3,4-b]quinolines via C-O and C-N bond formation. The scope of the reaction was further extended to o-ethynylquinoline-3-carbonitriles for the synthesis of alkoxy-substituted 3H-pyrrolo[3,4-b]quinolines using alcohols as nucleophiles. These reactions are regioselectively favoring the 5-exo-dig cyclizations in all the annulation processes.