Mild catalytic generation of CO2•− via photolysis of CO2 carbamate for hydrocarboxylation reactions

The conversion of carbon dioxide into value-added products has emerged as an alternative method to achieve net-zero emissions. While technologies that transform CO2 into fuels and chemical feedstocks have made great strides, the direct use of CO2 as C1 synthon for the formation of new carbon-carbon bonds remains a critical challenge. Herein, we present a new catalytic activation mode to generate CO2•− directly from CO2 under mild reaction conditions. Key to this methodology is the formation of a CO2 carbamate with a phenothiazine catalyst, which sets the required trigonal geometry for the release of CO2•− via photolysis upon absorption of visible light. The polarity-reversed CO2•− is employed in hydrocarboxylation reactions of alkenes and heterocycles. This protocol is distinguished by its wide substrate scope and broad applicability, even in the context of pharmaceutical cores. Given the mild and practical conditions, our chemistry can also be utilized for the synthesis of carbon-13 radiolabeled spirolactones using 13CO2.