Aryl Carboxylic Acids as Structure-Tunable HAT Agents for Photochemical Site-Selective C(sp3)-H gem-Difluoroallylation of Amides
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Updated: Jan 13, 2026

Achieving Moderate Pressures in Sealed Vessels Using Dry Ice As a Solid CO2 Source
Published on: August 17, 2018
Yujie Shan1, Fang-Qi Gao1, Chunhua Xu1
1State Key Laboratory for Development and Utilization of Forest Food Resources, Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing, Jiangsu 210037, China.
Abstract:
A photoredox-catalyzed strategy using aryl carboxylic acids as structure-tunable hydrogen atom transfer (HAT) agents is presented to enable the site-selective gem-difluoroalkenylation of C(sp3)-H bonds in amides under visible light. This redox-neutral method delivers up to 50:1 selectivity and 91% yield, tolerating diverse amide scaffolds and challenging α-trifluoromethyl alkyl alkenes. Late-stage functionalization of pharmaceuticals highlights its utility. Mechanistic studies reveal an aryl carboxyl radical-mediated HAT pathway, followed by radical addition, reduction, and β-fluoride elimination to furnish gem-difluoroalkenes.
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