Photoredox Activation of Formate Salts: Hydrocarboxylation of Alkenes via Carboxyl Group Transfer

A photoredox activation mode of formate salts for carboxylation was developed. Using a formate salt as the reductant, carbonyl source, and hydrogen atom transfer reagent, a wide range of alkenes can be converted into acid products via a carboxyl group transfer strategy in an additive-free fashion. Mechanistic studies revealed that radical anion species (CO2•– and carbon radical anions derived from the reduction of alkenes) are key intermediates of the transformation. This method has the advantages of high catalytic efficiency and a simple catalytic system, which may allow this approach to become a promising strategy for industrial applications.