Diastereoselective Aminoacylation of β-Methylstyrenes through Cooperative N-Heterocyclic Carbene and Photoredox Catalysis.

β-Amino ketones are versatile synthetic intermediates present in numerous biologically active compounds. Herein, we report a diastereoselective aminoacylation of β-methylstyrenes using acyl saccharins as bifunctional reagents to access β-amino ketones through cooperative N-heterocyclic carbene (NHC) and photoredox catalysis. The reaction proceeds via single-electron oxidation of the alkene to generate a radical cation, followed by nucleophilic addition and diastereoselective coupling between the resulting carbon-centered radical and an NHC-bound ketyl radical. This scalable method exhibits broad substrate scope and good functional group tolerance. Mechanistic studies support a radical pathway, and a plausible mechanism for this organocatalytic transformation is proposed.