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Perfluoroalkyl substances (PFAS) have been recognized as environmental pollutants. Hence, their efficient and mild destruction is a significant research interest. While many research articles and review papers have reported the cleavage of the C(sp2)−F bonds, single C(sp3)−F bond, and CF3 groups in PFAS, in this study, limited and emerging examples of a longer perfluoroalkyl group containing at least one repeating unit of 1,1,2,2‐tetrafluoroethylene was focused. In this Concept, we summarized recent progress on the chemical defluorination of PFAS via the cleavage of unactivated C(sp3)−F bonds in longer perfluoroalkyl groups under mild conditions (~150 °C). In addition to classical reductive defluorination, strategies featuring Lewis acid activation and the transient generation of an unsaturated bond were described. [ABSTRACT FROM AUTHOR]

Herein, we report the insertion of a difluoromethylene into 1,1,2,2-tetrafluoro-2-arylethyl copper complexes to synthesize extended perfluoroalkyl-bridged compounds that have various functional groups on each edge (ArCF2CF2(CF2)nR, R = arenes, halogens, alkyl, alkenyl, and benzyloxycarbonyl). Further, the one-pot syntheses of perfluoroalkyl-bridged compounds from aryl boronic acid esters were carried out. [ABSTRACT FROM AUTHOR]

Tetrafluoroethylene (TFE) is an industrial organofluorine feedstock that is used predominantly to fabricate fluorinated polymers. TFE exhibits excellent potential as a building block for synthesizing organofluorine compounds, which are increasingly gaining attention as functional materials, pharmaceuticals, and agrochemicals. In particular, the use of transition-metal complexes in the transformation of TFE is of great interest, considering their widespread use in syntheses of organofluorine compounds over the last few decades. This review highlights studies on the transformation of TFE into organofluorine compounds using transition-metal complexes, except for polymerizations. Our review covers cross-coupling reactions via C–F bond cleavage, fluoroalkylation reactions, multicomponent couplings, and olefin metathesis. 1 Introduction 2 Palladium Complexes 3 Copper Complexes 4 Nickel Complexes 5 Ruthenium Complexes 6 Rhodium Complexes 7 Summary and Perspective [ABSTRACT FROM AUTHOR]

Palladium‐catalyzed decarboxylative alkynylation of α‐acyloxyketones triggered by C(sp3)−O bond cleavage is disclosed. The decarboxylation strategy featuring a neutral reaction condition enabled an unprecedent catalytic alkynylation of a ketone enolate. The reaction was applied to a variety of substrates, giving desired products in good yields. We successfully obtained X‐ray crystallography of a new palladium–enolate intermediate that was synthesized by a reaction of [Pd(cod)(CH2TMS)2] with XPhos and α‐acyloxyketone at room temperature, indicating facile C(sp3)−O bond disconnection. [ABSTRACT FROM AUTHOR]

We describe the nickel-catalyzed hydrocarboxylation of ynamides with CO2 and H2O to afford a variety of α-amino-α,β-unsaturated esters with high regioselectivities. The selective α-carboxylation of ynamides with this catalytic protocol is unexpected in view of the electronic bias of ynamides and is in sharp contrast to our previous study in which a stoichiometric amount of Ni(0) was used to form a β-carboxylated product exclusively. We revealed that this unexpected C–C bond formation was induced by the combination of Zn and MgBr2. [ABSTRACT FROM AUTHOR]

A copper-catalyzed reaction of easily accessible a,a,a-trifluoromethylketones with various aldehydes affords difluoro-methylene compounds in the presence of diboron and NaOtBu. The key process of the reaction is the formation of a copper difluoroenolate by 1,2-addition of a borylcopper intermediate to α,α,α-trifluoromethylketones and subsequent b-fluoride elimination. Mechanistic studies including the isolation and characterization of a possible anionic copper alkoxide intermediate are also described. [ABSTRACT FROM AUTHOR]

Palladium-catalyzed decarboxylative alkynylation of α-acyloxyketones triggered by C(sp 3 )-O bond cleavage is disclosed. The decarboxylation strategy featuring a neutral reaction condition enabled an unprecedent catalytic alkynylation of a ketone enolate. The reaction was applied to a variety of substrates, giving desired products in good yields. We successfully obtained X-ray crystallography of a new palladium-enolate intermediate that was synthesized by a reaction of [Pd(cod)(CH 2 TMS) 2 ] with XPhos and α-acyloxyketone at room temperature, indicating facile C(sp 3 )-O bond disconnection., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We describe the nickel-catalyzed hydrocarboxylation of ynamides with CO 2 and H 2 O to afford a variety of α-amino-α,β-unsaturated esters with high regioselectivities. The selective α-carboxylation of ynamides with this catalytic protocol is unexpected in view of the electronic bias of ynamides and is in sharp contrast to our previous study in which a stoichiometric amount of Ni(0) was used to form a β-carboxylated product exclusively. We revealed that this unexpected C-C bond formation was induced by the combination of Zn and MgBr 2 .

An efficient and exceptionally mild intramolecular nickel-catalyzed carbon-oxygen bond-forming reaction between vinyl halides and primary, secondary, and tertiary alcohols has been achieved. Zinc powder was found to be an essential additive for obtaining high catalyst turnover and yields. This operationally simple method allows direct access to cyclic vinyl ethers in high yields in a single step., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This report describes the first Pd(0)-catalyzed cross-coupling of hexafluorobenzene (C6F6) with diarylzinc compounds to give a variety of pentafluorophenyl arenes. This reaction could be applied to other perfluoroarenes, such as octafluorotoluene, pentafluoropyridine, and perfluoronaphthalene, to give the corresponding polyfluorinated coupling products. The optimal ligand in this catalytic reaction was PCy3 , and lithium iodide was indispensable as an additive for the coupling reaction. One of the roles of lithium iodide in this catalytic reaction was to promote the oxidative addition of one C-F bond of C6F6 to palladium. Stoichiometric reactions revealed that an expected oxidative-addition product, trans-[Pd(C6F5)I(PCy3)2], generated from the reaction of [Pd(PCy3)2] with C6F6 in the presence of lithium iodide, was not involved in the catalytic cycle. Instead, a transient three-coordinate, monophosphine-ligated species, [Pd(C6F5)I(PCy3)], emerged as a potential intermediate in the catalytic cycle. Therefore, we isolated a novel Pd(II) complex, [Pd(C6F5)I(PCy3)(py)], in which pyridine (py) acted as a labile ligand to generate the transient species. In fact, in the presence of lithium iodide, this Pd(II) complex was found to react smoothly with diphenylzinc to give the desired pentafluorophenyl benzene, whereas the same reaction conducted in the absence of lithium iodide resulted in a decreased yield of pentafluorophenyl benzene, which indicated that the other role of lithium iodide was to enhance the reactivity of the organozinc species during the transmetalation step., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)