Photocatalytic Esterification of Ketones via C( <i>sp</i> ² )C( <i>sp</i> ³ ) Bond Activation

Carbon–carbon bond cleavage is a powerful strategy for molecular editing in synthetic chemistry; however, the selective activation of unstrained and unpolarized C–C σ ‐bonds remains challenging. In particular, controlled scission of C(CO)‐C linkages in ketones under mild conditions is rarely achieved. Herein, we report a redox‐neutral protocol for the direct conversion of ketones to esters via selective C( sp 2 )C( sp 3 ) bond cleavage. This transformation proceeds through a cascade sequence involving photoexcited oxygen radical anion ( 1 O 2 ). The reaction operates under mild conditions and exhibits high chemoselectivity, tolerating a wide range of sensitive functional groups. This method expands the scope of σ ‐bond activation and provides a practical approach for carbon–carbon bond transformations and late‐stage molecular modification.