Divergent Functionalization of 3-methyleneisoindolin-1-ones Enabled by Visible-Light Photoredox-Catalysis.

We present a redox-neutral strategy for the difunctionalization and C(sp2)-H alkylation of 3-methyleneisoindolin-1-ones using alkyl NHP esters as alkyl-radical precursors under visible-light irradiation. In the presence of alcohols, this approach affords difunctionalized products, while in the presence of a base, it yields C(sp2)-H alkylation products. The protocol offers several advantages, including metal-free, mild reaction conditions, a broad substrate scope, and compatibility with late-stage modification of pharmaceutically relevant molecules. Preliminary mechanistic investigations, such as Stern-Volmer quenching experiments, support an oxidative-quenching catalytic pathway and radical-clock, and EPR studies confirm the involvement of alkyl radicals.