Hydrogen-Bonded Electron Donor-Acceptor Complex Enables Markovnikov Hydroarylation and Hydroxyalkylation of N-Acyl Enamines.

Abstract

Visible-light-mediated electron donor-acceptor (EDA) complex catalysis has emerged as a powerful strategy for radical transformations under mild conditions, yet EDA donor catalytic systems driven by hydrogen bonding remain largely underexplored. Herein, we report a H-bonded EDA (H-EDA) donor catalysis system, employing thiols as donor catalysts to achieve Markovnikov hydroarylation and hydroxyalkylation of N-acyl enamines under redox-neutral conditions. This protocol proceeds under metal-free, base-free, and redox auxiliary-free conditions with complete atom economy. Mechanistic studies reveal that the reaction proceeds through oxidative nucleophilic coupling enabled by a photoinduced H-EDA complex via SET and 1,5-H-shift. The protocol features broad substrate scope, excellent regioselectivity, and gram-scale scalability. This work establishes a general H-EDA donor catalytic platform and redefines EDA donor catalysis beyond conventional redox auxiliary (RA)-mediated activation.