Photoinduced Iron-Catalyzed Aryl Ester Synthesis via C(sp2)-O Cross-Coupling of Carboxylic Acids with Anisoles

An efficient method for the synthesis of aryl esters was developed using photoinduced iron catalysis. The carboxylation of abundantly available anisoles proceeds via an aromatic radical substitution pathway. A broad range of carboxylic acids and anisoles were successfully coupled to afford aryl esters in moderate to good yields. Mechanistic studies revealed that (i) Fe(III) is reduced to Fe(II) along with the generation of a chloride radical through a visible-light-induced ligand-to-metal charge transfer (LMCT) process; (ii) the carboxy radical is formed via hydrogen atom transfer (HAT) from the carboxylic acid to the chloride radical; (iii) Fe(III) promotes ipso-substitution by interacting with the electronegative oxygen atom of the anisole to facilitate the aryl esters synthesis.