Oxidative Quenching-Enabled, NHC-Catalyzed Diastereoselective Aminoacylation of ( <i>Z</i> / <i>E</i> )-β-Methylstyrenes with Benzoyl Saccharin

Stereoconvergent difunctionalization of <i>Z</i>/<i>E</i>-mixed alkenes presents a fundamental challenge in organic synthesis. We herein report a dual NHC/photoredox catalytic system that addresses this challenge through oxidation of internal alkenes to radical cation intermediates. These activated species undergo a cascade sequence involving nucleophilic addition followed by radical-radical cross-coupling, achieving stereoconvergent aminoacylation of various <i>Z</i>/<i>E</i>-alkene mixtures and delivering β-amino ketones in high yields with exclusive diastereocontrol. The strategic implementation of benzoyl saccharin as a bifunctional reagent is crucial, serving simultaneously as an acyl radical precursor and a nucleophilic amine source. Mechanistic investigations establish the indispensable role of the saccharin moiety in governing diastereoselectivity. This work introduces a new paradigm for radical-mediated difunctionalization, significantly expanding access to stereodefined architectures from complex alkene feedstocks.