Metal-Free Photoredox Phosphonation of C–N and C–X Bonds in Aqueous Solvent Mixtures

Aryl phosphonate esters are valuable moieties for the pharmaceutical and agrochemical industries. Accessing such compounds from affordable and abundant phosphite reagents and a wide range of aromatic building blocks under metal-free, visible light-induced reaction conditions would represent a desirable technology. Herein, we present an efficient and mild methodology for the synthesis of aromatic phosphonate esters in good to excellent yields using DBU and phenothiazine as a photoredox catalyst. The reaction exhibits wide functional group compatibility enabling the transformation in presence of ketone, amide, ester, amine, and alcohol moieties. Importantly, the reaction proceeds using a green solvent mixture primarily composed of water, thus lowering the environmental footprint of this transformation compared to current methods.