UVA-Light-Promoted Catalyst-Free Photochemical Aerobic Oxidation of Boronic Acids

Abstract

The hydroxy group, and the phenol moiety in particular, is ubiquitous in several natural products, in organic synthesis and/or pharmaceutical industry. With the uprise of photoredox catalysis, many efforts worldwide focus on developing novel and sustainable protocols, providing an easy access to hydroxy-containing molecules. Boronic acids and boronic ester derivatives are considered valuable precursors for the synthesis of hydroxy group derivatives. Herein, we report a novel, sustainable, light-driven protocol, where the impact of wavelength irradiation on boronic acid aerobic photooxidation was examined. In this work, UVA-light (370 nm) irradiation was found to promote the photocatalyst-free aerobic oxidation of boronic acids and boronic acid derivatives. Furthermore, a broad scope of substrates was tested, and extensive mechanistic studies were performed in order to probe the reaction mechanism.