Photoredox Conversion of Phenol Derivatives Into β ‐Arylpropionic Acids via Radical 1,4‐Aryl Migration

ABSTRACT Phenols, the most abundant renewable arene resource from lignins, are not only important fine chemicals and feedstocks but also widely present in natural products and pharmaceutical molecules. Achieving their valorization and late‐stage functionalization is of great scientific value and broad application prospects. Herein, we report a novel C─C bond formation of phenols in which a visible‐light‐driven photoredox catalytic system mediates 1,4‐aryl migration initiated by trifluoromethyl or sulfonyl radicals, enabling efficient conversion of phenolic derivatives into β ‐arylpropionic acids via C─O bond cleavage. The transformation exhibits broad functional‐group tolerance, enables modular installation of fluoroalkyl and sulfonyl groups, accommodates diverse migrating aryl groups, and has been demonstrated in the late‐stage functionalization of 11 complex phenolic natural products and drug derivatives. Notably, this study represents the application of a reductive radical–polar‐crossover process to a 1,4‐aryl migration involving aryl C─O bond heterolytic cleavage, enabling efficient C─O bond activation and effective suppression of undesired CO 2 extrusion. Density functional theory (DFT) calculations support the proposed mechanism and elucidate the origin of the suppression of the decarboxylation pathway.