Photoredox-Mediated Mono- and Difluorination of Remote Unactivated Methylene C(sp<sup>3</sup>)–H Bonds of <i>N</i>-Alkyl Sulfonamides
Zhiqiang Deng, Zhenxiang Zhao, Gang He, Gong Chen
Abstract
)-H fluorination of sulfonyl-protected primary alkylamines with Selectfluor is developed. The reaction can proceed in excellent monofluorination selectivity for amine substrates without α substituent. For α-substituted substrates, a slightly modified reaction conditions with two rounds of operation gives the δ,δ-difluorination products in good yield. Mechanistic studies suggest SET oxidation of sulfonamide group directly generates the key sulfonamide N radical intermediate, which triggers a 1,5-HAT process to form the δ alkyl radical.
Topics & Concepts
ChemistrySulfonamideSelectfluorSubstituentSulfonylAlkylYield (engineering)Amine gas treatingMedicinal chemistryRadicalSelectivityMethyleneCombinatorial chemistryOrganic chemistryCatalysisMaterials scienceMetallurgyFluorine in Organic ChemistryCatalytic C–H Functionalization MethodsRadical Photochemical Reactions