Visible light promoted and chlorophyll catalyzed α-oxidation of amines to amides under aerobic conditions: Synthesis of 3,4-dihydroisoquinolin-1(2H)-ones and N-phenyl oxalamides

Abstract

A novel method for the metal-free synthesis of 3,4-dihydroisoquinolin-1(2H)-ones and N-phenyl oxalamides from 1,2,3,4-tetrahydronisoquinoline and N-phenyl glycine derivatives based on visible-light photoredox catalysis under aerobic conditions is reported. Natural pigment chlorophyll is used as photosensitizer to generate singlet molecular oxygen 1O2, which is involved in the aerobic α-oxidation of N-phenyl amines. The protocol provides amides in good yields at room temperature under mild conditions. Based on the experimental results, a plausible photoredox mechanism is proposed.