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

Numerous reports invoke Cu^III–F intermediates engaging in oxidative cross-couplings mediated by low/mid-valent copper and formal sources of ‘F⁺’ oxidants. These elusive and typically instable Cu^III 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 C_sp–CF₃ bond formation upon addition of silyl-capped alkynes following a 2 e^– Cu^III/Cu^I redox shuttle. This finding strongly supports the intermediacy of Cu^III fluorides in C–C coupling. We review herein the state of the art about well-defined Cu^III fluorides enabling cross-coupling reactions.

1 Introduction

2 Brief History of Coupling-Competent Cu^III Fluorides

3 Design of an Isolable – yet Reactive – Organocopper(III) Fluoride

4 Alkyne Trifluoromethylation: Scope and Mechanism

5 Extension to Aryl–CF₃ and C–Heteroatom Couplings

6 Summary and Outlook