Metal-Free, Room-Temperature, Radical Alkoxycarbonylation of Aryldiazonium Salts through Visible-Light Photoredox Catalysis

The first radical alkoxycarboxylation of aryldiazonium salts using CO gas through visible-light-induced photo-redox catalysis (16 W blue LEDs) has been developed. This reaction is entirely metal-free, is carried out at room temperature with a low loading of an organic dye as a photocatalyst (0.5 mol%), and provides a wide range of arylcarboxylic acid esters in high yields. Importantly, this photocatalytic system can be successfully extended to other carboxylation reactions.