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This paper describes the one-electron interconversions of isolable NiIII and NiIV complexes through their reactions with carbon-centered radicals (R•). First, model NiIII complexes are shown to react with alkyl and aryl radicals to afford NiIV products. Preliminary mechanistic studies implicate a pathway involving direct addition of a carbon-centered radical to the NiIII center. This is directly analogous to the known reactivity of NiII complexes with R•, a step that is commonly implicated in catalysis. Second, a NiIV-CH3 complex is shown to react with aryl and alkyl radicals to afford C-C bonds via a proposed SH2-type mechanism. This pathway is leveraged to enable challenging H3C-CF3 bond formation under mild conditions. Overall, these investigations suggest that NiII/III/IV sequences may be viable redox pathways in high-oxidation-state nickel catalysis.

A palladium-catalyzed cross-coupling of aryl chlorides/bromides with TMSCF2H is described. Two different catalysts, Pd(dba)2/BrettPhos and Pd(PtBu3)2, are demonstrated and provide a variety of difluoromethylated arenes in good yields.

An isolable pyridinium trifluoromethoxide salt is prepared from the reaction of 4-dimethylaminopyridine with the commercially available liquid 2,4-dinitro(trifluoromethoxy)benzene. The salt is an effective trifluoromethoxide source for SN2 reactions to form trifluoromethyl ethers.

This article describes a detailed investigation of ligand effects on Ph–CF3 coupling from phosphinoferrocene-ligated PdII(Ph)(CF3) complexes. This study reveals that increasing the size of the phosphine substituents results in an enhanced rate of Ph–CF3 coupling, with (DtBPF)Pd(Ph)(CF3) (DtBPF = 1,1′-bis(di-tert-butylphosphino)ferrocene) being the most reactive complex. The mechanism of Ph–CF3 bond formation from both (DtBPF)Pd(Ph)(CF3) and (DiPrPF)Pd(Ph)(CF3) (DiPrPF = 1,1′-bis(diisopropylphosphino)ferrocene) was interrogated experimentally and computationally. These studies implicate a pathway involving concerted Ph–CF3 bond-forming reductive elimination from the four-coordinate PdII centers. An alternative pathway involving α-fluoride elimination and subsequent PhF2C–F coupling from PdII(CF2Ph)(F) intermediates was also evaluated but was ruled out based on DFT as well as the independent synthesis and reactivity studies of (DiPrPF)Pd(CF2Ph)(F).

A palladium-catalyzed cross-coupling of aryl chlorides/bromides with TMSCF

A method for the room temperature deoxyfluorination of benzaldehydes and α-ketoesters using sulfuryl fluoride and Me4NF is described. A large scope of aryl and heteroaryl substrates is demonstrated, and this method compares favorably to other common deoxyfluorination methods for many substrates.

This Communication describes studies of Ph–RF (RF = CF3 or CF2CF3) coupling at Pd complexes of general structure (PtBu3)PdII(Ph)(RF). The CF3 analogue participates in fast Ph-CF3 coupling (

This paper describes the development of Pd-catalyzed inter- and intramolecular direct arylation using mesylates. Furthermore, a sequential mesylation/arylation protocol using phenols as substrates is described. These transformations are general with respect to the electronics of the C–H substrates and allow for the synthesis of diverse heterocyclic motifs in good yields. Both arenes and heteroarenes efficiently participate in these reactions. Preliminary mechanistic studies are presented for both inter- and intramolecular arylations.

This paper describes a method for nickel catalyzed intramolecular C–H arylation using aryl pivalates as electrophiles. The transformation is efficient for the synthesis of diverse electronically and sterically differentiated dibenzofurans. Additionally, the method could be expanded toward the synthesis of carbazoles. Preliminary mechanistic studies of the transformation are also described.

The title reaction is efficient for the synthesis of electronically and sterically differentiated dibenzofurans.