On the Existence and Relevance of Copper(III) Fluorides in Oxidative Trifluoromethylation

Numerous reports invoke CuIII–F intermediates engaging in oxidative cross-couplings mediated by low/mid-valent copper and formal sources of ‘F+’ oxidants. These elusive and typically instable CuIII fluorides have been rarely characterized or spectroscopically identified, making their existence and participation within catalytic cycles somehow questionable. We have authenticated a stable organocopper(III) fluoride that undergoes Csp–CF3 bond formation upon addition of silyl-capped alkynes following a 2 e– CuIII/CuI redox shuttle. This finding strongly supports the intermediacy of CuIII fluorides in C–C coupling. We review herein the state of the art about well-defined CuIII fluorides enabling cross-coupling reactions. 1 Introduction 2 Brief History of Coupling-Competent CuIII Fluorides 3 Design of an Isolable – yet Reactive – Organocopper(III)