Visible light-induced oxidative α-hydroxylation of β-dicarbonyl compounds catalyzed by ethylenediamine-copper(ii).

We have developed an efficient oxidative α-hydroxylation of β-keto esters with firstly using the structurally simple ethylenediamine-copper(ii) as a catalyst for β-keto esters activation and using visible light as the driving force for generating more active singlet oxygen (1O2) from triplet state oxygen (3O2) in the air, providing a series of α-hydroxy β-keto esters in excellent yields (up to 99%) under extremely low photosensitizer loading (0.01 mol%) and catalyst loading (1 mol%) within a short time. Moreover, the gram-scale synthesis showed the practical utility of this protocol.