Visible Light‐Induced Salan‐Copper(II)‐Catalyzed Enantioselective Aerobic α‐Hydroxylation of β‐Keto Esters

A strategy of visible light‐induced salan‐copper(II)‐catalyzed asymmetric α‐hydroxylation of β‐keto ester with utilization of sustainable air as the oxidant was developed. This protocol allows convenient access to a number of enantioenriched α‐hydroxyl β‐keto esters (up to 95% yield, 96% ee), especially for β‐keto methyl esters that are valuable architectures in pharmaceuticals, including the key intermediate of the sodium‐channel blocker (S)‐indoxacarb. Experimental studies suggest that reactive singlet oxygen may participate in this reaction.