Visible-Light-Photosensitized Aryl and Alkyl Decarboxylative Functionalization Reactions

Despite significant progress in aliphatic decarboxylation, an efficient and general protocol for radical aromatic decarboxylation has lagged far behind. Herein, we describe a general strategy for rapid access to both aryl and alkyl radicals by photosensitized decarboxylation of the corresponding carboxylic acids esters followed by their successive use in divergent carbon-heteroatom and carbon-carbon bond-forming reactions. Identification of a suitable activator for carboxylic acids is the key to bypass a competing single-electron-transfer mechanism and switch on an energy-transfer-mediated homolysis of unsymmetrical sigma-bonds for a concerted fragmentation/decarboxylation process.