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

We have developed an efficient oxidative alpha-hydroxylation of beta-keto esters with firstly using the structurally simple ethylenediamine-copper(ii) as a catalyst for beta-keto esters activation and using visible light as the driving force for generating more active singlet oxygen (O-1(2)) from triplet state oxygen (O-3(2)) in the air, providing a series of alpha-hydroxy beta-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.