Dual-role iron species in photoelectrocatalytic radical trifluoromethylation with trifluoroacetates

TL;DR

This paper introduces a new method for adding trifluoromethyl groups to molecules using light and electricity, avoiding harmful byproducts and making the process more sustainable.

Contribution

The study introduces a dual-function iron species in a photoelectrocatalytic system for efficient trifluoromethylation without stoichiometric oxidants.

Findings

The method uses in situ-generated iron species to enable C(sp²)–H trifluoromethylation without stoichiometric oxidants.

The process produces traceless byproducts and works under mild, tunable, and scalable conditions.

It allows functionalization of diverse (hetero)cyclic scaffolds, including electron-rich and easily oxidizable substrates.

Abstract

Trifluoromethylation remains a fundamental transformation in drug discovery, underpinning many top-selling pharmaceuticals. Emerging developments in iron ligand-to-metal charge transfer (LMCT) catalysis have redefined fluoroalkylation chemistry by unlocking the repurposing of readily available trifluoroacetates as radical trifluoromethyl sources. Recent (hetero)arene trifluoromethylation methods generally require stoichiometric inorganic oxidants to turnover photoactive iron catalysts, thereby limiting their broader applicability. Herein, we present an integrated photoelectrocatalytic strategy employing in situ-generated multifunctional iron species to achieve C(sp²)–H trifluoromethylation without stoichiometric oxidants and generating only traceless byproducts. Mechanistic studies identify catalytically active iron species exhibiting a dual synergistic function: promoting the photodecarboxylation of trifluoroacetates and mediating catalytic redox turnover. This protocol offers mild, tunable, and scalable conditions powered by visible light and electric current. It features a broad substrate scope, enabling the functionalization of diverse (hetero)cyclic scaffolds, including challenging electron-rich and easily oxidizable substrates, thus demonstrating its potential for sustainable late-stage modification in pharmaceutical synthesis.

Recent (hetero)arene trifluoromethylation methods generally require stoichiometric inorganic oxidants to turnover photoactive iron catalysts, thereby limiting their broader applicability. Herein, the authors report an integrated photoelectrocatalytic strategy employing in situ-generated multifunctional iron species to achieve C(sp²)–H trifluoromethylation without stoichiometric oxidants and generating traceless byproducts.

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