Enantio- and Diastereoselective Tandem Giese Addition/Homolytic Aromatic Substitution Reaction via Visible-Light Photoredox Catalysis

The wide spectrum of biological activities of tetrahydroquinolines (THQs) has prompted the extensive development of synthetic strategies. While photoredox catalysis has emerged as a powerful approach for THQ synthesis, achieving asymmetry remains challenging due to the high reactivity of the radicals. Here we report enantio- and diastereoselective tandem Giese addition/homolytic aromatic substitution reactions via visible-light photoredox catalysis. Using a chiral oxazaborolidinium ion catalyst and photosensitizer, the reaction of α-aminoalkyl radicals with α,β-unsaturated esters provided high yields (up to 97%) of the desired THQs with high enantio- and diastereoselectivities (up to 99% ee and formation of only trans-diastereomer) in a single step.