Visible light mediated sp~3 C-H bond functionalization of N-aryl-1,2,3,4-tetrahydroisoquinolines via Ugi-type three-component reaction

摘要

An efficient and high yield process for sp3 C-H bond functionalization of N-aryl-1,2,3,4-tetrahydroisoqui-nolines is disclosed. This involves a visible light mediated photoredox Ugi-type reaction with carboxylic acids and isonitriles under aerobic conditions, employing Ru(bpy)_3Cl_2 as a photoredox catalyst and CH_3CN as the solvent. CH_3CN was found to be crucial for the process, and good to excellent yields were achieved for a wide variety of N-aryl-1,2,3,4-tetrahydroisoquinolines, carboxylic acids, and isonitriles. The developed methodology is attractive for the synthesis of a library of 1,2,3,4-tetrahydroisoquinolines.