CO2 Radical Anion in Photochemical Dicarboxylation of Alkenes.

CO2 radical anion (CO2⋅−) is a highly reductive species (Ered=−2.2 V vs SCE), which can undergo Giese radical addition to an unsaturated C−C bond and install a carbonyl group to synthesize acids. Normally, it has been generated through the direct reduction of CO2 gas or from formate salts via HAT (hydrogen atom transfer) as the BDE (bond dissociation energy) of the C−H bond in formate is only around 86 kcal/mol. This concept highlights the recent developments on alkenes dicarboxylation reaction with CO2 and/or formate as the carbonyl sources. In these reactions, CO2 radical anion species played significant roles in the carboxylation step. [ABSTRACT FROM AUTHOR]