Non-decarboxylative C–H Fluorination of Carboxylic Acids by Iridium Photocatalysis

We have developed a photoredox-initiated non-decarboxylative C–H fluorination of carboxylic acids. Using Selectfluor as the fluorinating agent, a range of primary and secondary carboxylic acids were site-selectively fluorinated at their β- to ϵ-positions. Mechanistic studies suggest that the reaction proceeds by photocatalytic reduction of Selectfluor, generating an N-centered radical that mediates intermolecular hydrogen atom abstraction and propagates a radical chain fluorination process.