Visible light mediated sp3 C–H bond functionalization of N-aryl-1,2,3,4-tetrahydroisoquinolines via Ugi-type three-component reaction

Abstract

An efficient and high yield process for sp³ C–H bond functionalization of N-aryl-1,2,3,4-tetrahydroisoquinolines is disclosed. This involves a visible light mediated photoredox Ugi-type reaction with carboxylic acids and isonitriles under aerobic conditions, employing Ru(bpy)₃Cl₂ as a photoredox catalyst and CH₃CN as the solvent. CH₃CN 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.