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A metal-free strategy to access tertiary difluoromethylene-containing molecules from RCF₂H (R = aryl, H, F) precursors, vinyl-pinacol boronic ester (BPin) reagents, and proradical reagents is reported. 

To develop synthetic strategies to construct ligands containing secondary sphere acids, we demonstrate that an appended borane of low Lewis acidity (–BPin) can be upgraded to a strong Lewis acid (–BF2). Using a pyridine-pyrazole ligand coordinated to Mo(CO)4, we show that a pendent –BPin group undergoes exhaustive fluorination to –BF3K, a precursor to a highly acidic –BF2 unit (acceptor number ~15x greater than –BPin). 

Abstract We report copper(II) and copper(III) trifluoromethyl complexes supported by a pyridinedicarboxamide ligand (L) as a platform for investigating the role of electron transfer in C(sp²)−H trifluoromethylation. While the copper(II) trifluoromethyl complex is unreactive towards (hetero)arenes, the formal copper(III) trifluoromethyl complex performs C(sp²)−H trifluoromethylation of a wide range of (hetero)arenes. Mechanistic studies using the copper(III) trifluoromethyl complex suggest that the mechanism of arene trifluoromethylation is substrate‐dependent. When the thermodynamic driving force for electron transfer is high, the reaction proceeds through a previously unidentified single electron transfer (SET) mechanism, where an initial electron transfer occurs between the substrate and oxidant prior to CF₃group transfer. Otherwise, a CF₃radical release/electrophilic aromatic substitution (S_EAr) mechanism is followed. These studies provide valuable insights into the role of strong oxidants and potential mechanistic dichotomy in Cu‐mediated C(sp²)−H trifluoromethylation. 

The selection of electronically-different thiolate-based photosensitizers is employed to achieve a precise and specific C–F bond defluorination of a broad range of trifluoromethylarenes, enabling the synthesis of 88 α,α-difluoromethyl compounds. 

We report a metal-free strategy to access fluoroalkyl–olefin linkages from RCF₂H (R = aryl, H, F and fluoroalkyl) precursors and vinyl-pinacol boronic ester (BPin) reagents. 

Fluorine-containing allyl compounds are prevalent in drugs and bioactive molecules. Here, we report a straightforward and efficient radical pentafluorosulfanylation of allyl sulfones using sulfur chloride pentafluoride (SF₅Cl) to synthesize structurally diverse pentafluorosulfanyl allylic compounds. This transformation exhibits excellent functional group tolerance and achieves an impressive isolated yield of up to 98% in just 1 minute under ultraviolet light. Mechanistic studies suggest that the sulfonyl group acts as a free radical leaving group, with the capability of abstracting the chlorine atom from SF₅Cl. This radical chain propagation pathway facilitates the rapid regeneration of the sulfur pentafluoride radical, resulting in a notably high quantum yield. Moreover, this light-driven radical pentafluorosulfanylation simplifies the synthetic pathway to modify complex and bioactive molecules. In addition, the drug-modified pentafluorosulfanyl compounds exhibited promising effects in inhibiting cancer cell proliferation, both in vitro and in vivo. Therefore, this protocol provides a practical synthetic route to radical pentafluorosulfanylation, highlighting its potential in drug discovery. 

The ability of a phosphine-appended-2,2′-bipyridine ligand ((Ph 2 P) 2 bpy) to serve as a platform for late-stage ligand modifications was evaluated using tetrahedral (Ph 2 P) 2 bpyFeCl 2 . We employed a post-metalation Staudinger reaction to install a series of functionalized arenes, including those containing Brønsted and Lewis acidic groups. This reaction sequence represents a versatile strategy to both tune the ligand donor properties as well as directly incorporate appended functionality. 

A series of zerovalent iron complexes were synthesized that contain allylic substituents attached to a 2,6-bis(imidazol-2-ylidene)pyridine pincer ligand. These species varied in the identity of their ancillary ligands and were used to study the requirements and limitations of late-stage hydroboration. While late-stage ligand functionalization can facilitate the incorporation of Lewis acidic boranes into a ligand scaffold, thereby alleviating Lewis acid/base incompatibilities of the free ligand, we identify and discuss complicating factors that arise from complexes containing labile M–L bonds.