A strategy of visible light-induced salancopper(II)-catalyzed asymmetric a-hydroxylation of b-keto ester with utilization of sustainable air as the oxidant was developed. This protocol allows convenient access to a number of enantioenriched a-hydroxyl b-keto esters (up to 95% yield, 96% ee), especially for b-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.Recently, visible light photocatalysis has offered a technically attractive and energy-saving platform for aerobic oxidation. [1] In particular, the reactivity of singlet oxygen ( 1 O 2 ) has been applied to visible light activated asymmetric catalysis in recent years. [2] However, the stereoselectivity control of the enantioselective hydroxylation reaction using photogenerated 1 O 2 as the terminal oxidant still remains a challenge, and work in this field has rarely been reported. [3] Specifically, our group first reported on the chiral phasetransfer catalyzed aerobic transformation using tetraphenylporphyrin (TPP) as the photosensitizer (Scheme 1b), [3a] while Xiao et al. reported the asymmetric aerobic oxidation reaction by bifunctional photocatalyst-Ni(II) catalysis (Scheme 1c). [3c] However, current methods are limited in application due to their dependence on the use of either structurally complex catalysts or the steric induction of substrate itself to generate the requisite chiral environment.Enantioenriched a-hydroxy b-keto esters, and particularly the those containing methyl ester compounds, are prevalent in a wide range of bioactive natural products and pharmaceuticals, [4] including Kjellmanianone, [5] Vindoline, [6] Hamigeran A, [7] and Indoxacarb (Scheme 1a). [8] However, in previous studies, consistently high yields and enantioselectivities were achieved only for the b-keto esters bearing bulky ester groups, [3,9] and an additional transesterification step is required for synthesis of the abovementioned biological molecules. Given these important advances, the direct enantioselective hydroxylation of valuable b-keto esters from sustainable, environmentally benign molecular oxygen remains an important yet elusive goal. Within this field, we sought to develop a new approach based on asymmetric photocatalysis to provide highly enantioselective access toward a broad range of a-hydroxy b-keto ester bearing smaller ester groups; such esters are highly valuable architectures but are challenging and difficult to achieve directly.We started our study of this topic by investigating the asymmetric a-hydroxylation of 5-chloro indanone carboxylic methyl ester 1 a that served as the model reaction. In previous work, we demonstrated that using cumene hydro peroxide as the oxidant, the salan-Zr complex [10] can catalyze the a-hydroxylation of b-keto methyl esters with excellent yields and enantioselectivities. Inspired by this result, we became interested in further explo...