Photocatalytic CO₂-Promoted Divergent C(sp³)–H Carboxylation of Benzyl Alcohols

Abstract

While carbon dioxide is extensively utilized as a C1 building block, catalytic strategies that seamlessly merge its roles as both transient promoter and terminal electrophile for direct C–H carboxylation remain rare. Herein, we report photocatalytic CO₂-promoted divergent C(sp³)–H carboxylation of benzyl alcohols. This transformation is enabled by "Two-in-One" strategy, wherein CO₂ serves a dual role: transient electronic modulator through in situ carbonate formation, and simultaneously functioning as the carboxyl source. This protocol features mild conditions and broad functional group tolerance, delivering a wide array of α-hydroxy acids with high atom- and step-economy. Notably, this catalytic system enables a switchable divergent pathway, facilitating a challenging sequential C–H activation to achieve 1,1-dicarboxylation. These advances represent a versatile and practical platform for the valorization of simple alcohols into complex, value-added functionalized acids using CO₂.