Visible-light-driven α-hydroxylation of β-dicarbonyl compounds mediated by NaI/NPh3 or NaI/PPh3 in water

Abstract

The synthesis of α-hydroxy carbonyl compounds through the electron donor–acceptor (EDA) complex system in an aqueous phase has not been reported previously. This report presents a novel and efficient EDA complex system employing β-dicarbonyl substrates that do not require previous installation, NaI and inexpensive NPh₃. The purpose of constructing this EDA complex is to improve and advance the EDA photocatalytic system in the aqueous phase, while maintaining tolerance to oxygen. The complexes were used to realize the hydrogen evolution reaction and hydration–hydroxylation of β-dicarbonyl derivatives in a non-homogeneous system using water as the solvent and oxygen source. The reaction exhibits broad substrate compatibility, does not need phase-transfer catalysts or additional oxidants, is alkali-free and metal-free, and allows microreactor gram-scale preparation. The reaction not only is suitable for liquid matrices but also can achieve the desired yield through an increase in the concentration of the green solvent ethanol, when the light transfer is obstructed by insoluble solid matrices.