Rapid access to 3-(aminomethyl)isoquinoline-fused polycyclic compounds by copper-catalyzed four-component coupling, cascade cyclization, and oxidation.

A novel copper-catalyzed synthesis of 3-(aminomethyl)isoquinoline-fused polycyclic compounds, through four-component coupling, cyclization, and oxidation, has been developed. A Mannich-type reaction of 2-ethynylbenzaldehyde with paraformaldehyde and a secondary amine followed by treatment with a diamine component gave tricyclic isoquinolines through cascade cyclization and oxidation. Construction of fused isoquinolines of various ring sizes is also presented.