Photocatalytic 1,3-dicarboxylation of unactivated alkenes with CO2

Photocatalytic carboxylation with CO2 is a powerful strategy for the synthesis of functionalized carboxylic acids and their derivatives under mild conditions. However, the dicarboxylation of alkenes with CO2 is still underdeveloped and confined to the formation of only two C–C bonds. Herein, we report the 1,3-dicarboxylation of unactivated alkenes with CO2 via 1,2-aryl migration, which involves the cleavage of one C–C bond and the formation of three C–C bonds. This visible-light photocatalytic protocol is also distinguished by good functional group tolerance, broad substrate scope, and facile derivations of products to heterocyclic scaffolds. Mechanistic studies indicate that the in situ generated formate could act as the radical precursor of CO2˙−, and the following radical addition, 1,2-aryl migration, single electron reduction, and nucleophilic attack at the second CO2 would afford the dicarboxylic acids.