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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]

We herein report a nickel‐catalyzed migratory cycloisomerization of o‐alkynylanilides, giving 2,3‐disubstituted indoles in good yields. The cyclization proceeded via acyl transfer on the nitrogen atom of the substrate to C3‐position in the product, and an N‐heterocyclic carbene (NHC) ligand such as ICy or SICy was found to be suitable in this reaction. It was thought that the reaction proceeds via an aza‐nickelcyclepentene intermediate formed from alkyne and the C=O bond of the amide moiety in o‐alkynylanilides. [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]

We herein report palladium(0)-catalyzed decarboxylative cyclization of α-acyloxyketones having an allene moiety in the tether, giving various cyclohexanone derivatives. DFT calculations suggested that the reaction proceeds in the following sequence: (1) oxidative addition of the C(α)–O bond of α-acyloxyketones 1 to a palladium(0) complex; (2) insertion of the terminal allene double bond into the Pd–C(sp3) bond to form a C–C bond between the α-carbon of the carbonyl group and the β-carbon in the allene; (3) decarboxylation; and (4) reductive elimination to form a C(sp3)–C(sp) bond. The DFT calculations also rationalized why the reaction gives a 6-membered product instead of a 5- or 7-membered product. [ABSTRACT FROM AUTHOR]

Summary: Since methylotrophic yeasts such as Ogataea methanolica can use methanol as a sole carbon feedstock, they could be applied to produce valuable products from methanol, a next‐generation energy source synthesized from natural gases, using genetic engineering tools. In this study, metabolite profiling of O. methanolica was conducted under glucose (Glc) and low and high methanol (L‐ and H‐MeOH) conditions to show the adaptation mechanism to a H‐MeOH environment. The yeast strain responded not only to the presence of methanol but also to its concentration based on the growth condition. Under H‐MeOH conditions, O. methanolica downregulated the methanol utilization, glycolytic pathway and alcohol oxidase (AOD) isozymes and dihydroxyacetone synthase (DAS) expression compared with L‐MeOH‐grown cells. However, levels of energy carriers, such as ATP, were maintained to support cell survival. In H‐MeOH‐grown cells, reactive oxygen species (ROS) levels were significantly elevated. Along with increasing ROS levels, ROS scavenging system expression was significantly increased in H‐MeOH‐grown cells. Thus, we concluded that formaldehyde and H2O2, which are products of methanol oxidation by AOD isozymes in the peroxisome, are overproduced in H‐MeOH‐grown cells, and excessive ROS derived from these cells is generated in the cytosol, resulting in upregulation of the antioxidant system and downregulation of the methanol‐utilizing pathway to suppress overproduction of toxic intermediates. [ABSTRACT FROM AUTHOR]

Herein, we report the nickel‐catalyzed cascade C−O bond cleavage/cyclization of ortho‐alkynylphenyl ester to construct a 3‐acylbenzo[b]furan skeleton. As a result of reaction condition screening, the Ni(0)/IAd (1,3‐Di(1‐adamantyl)imidazole‐2‐ylidene) system was found to be optimal for catalytic conversion. Interestingly, the reaction exclusively gives 3‐acylbenzo[b]furan instead of a decarbonylated product frequently observed in reactions mediated by acyl‐nickel species. The catalyst loadings could be reduced to 5–10 mol %. We demonstrated the synthesis of a variety of functionalized 3‐acylbenzofuran derivatives. We conducted stoichiometric study of nickel complexes as well as density functional theory (DFT) calculations to support a possible reaction mechanism. [ABSTRACT FROM AUTHOR]

A nickel-catalyzed β-selective hydrocarboxylation of ynamides to give protected dehydro-β-amino acids was developed. The key to exclusive β-selectivity was the use of diethylzinc as a reductant in the presence of a magnesium salt. The reaction was conducted with bis(acetylacetonato)nickel(II) instead of costly and sensitive bis(1,5-cyclooctadiene)nickel(0). In addition, the optimized ligand was inexpensive 1,5-cyclooctadiene. Investigation of the substrate scope revealed that both nitrogen and alkyne substituents have marked effects on the reaction efficiency. We obtained experimental clues that indicated the formation of a vinylzinc intermediate that forms a C–C bond with CO2. [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 developed a conceptually and methodologically novel ruthenium(0) nanoparticle catalyst, sulfur-modified Au-supported ruthenium nanoparticles (SARu). SARu is easily prepared through a three-step procedure involving simultaneous in situ metal nanoparticle and nanospace organization. This unique method does not require any conventional preformed template to immobilize and stabilize metal nanoparticles. SARu is an ideal ruthenium catalyst for liquid-phase combinatorial synthesis because it repeatedly catalyzes ligand-free Suzuki–Miyaura coupling of aryl halides, including aryl chlorides, with arylboronic acids with low Ru leaching. Physical analysis of SARu showed that the active species in these reactions were ruthenium (0) nanoparticles with a size of 1–3 nm. Also, we developed a continuously irradiating microwave methodology, which can first time discriminate the heating effect and the microwave effect in microwave experiments. [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]

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. [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]

This report describes the first Pd0-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 PdII 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 PdII 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. [ABSTRACT FROM AUTHOR]

Aims/Background: Many epidemiological studies of new hepatitis viruses, including GB virus C (GBV-C) and hepatitis G virus (HGV), have used polymerase chain reaction (PCR) primers designed for the third nonstructural region (NS3R). However, a homology study of GBV-C and HGV genomes revealed that the 5′ untranslated region (5'UTR) was more conserved than NS3R. Methods: We attempted to detect GBV-C/HGV using PCR primers corresponding to the 5′ UTR, and compared its incidence to that derived from NS3R primers. Furthermore, PCR products amplified using the 5′ UTR primers were sequenced and subjected to phylogenetic analysis. Results: In patients with chronic hepatitis C, the prevalence of GBV-C/HGV by PCR with the NS3R and 5′ UTR primers was 5.1% (4/78) and 17.9% (14/78), respectively, and in patients on hemodialysis, it was 0% (0/81) and 5.9% (5/85), respectively. We could not detect GBV-C/HGV in patients with non-A-C liver disease. The incidence of GBV-C/HGV by 5′ UTR primers was higher than by NS3R primers. After DNA sequencing at 5′ UTR, phylogenetic analysis showed two types of GBV-C/HGV, Jap and HGV types. Conclusion: 5′ UTR primers proved highly sensitive for detection of GBV-C/HGV and were superior to the NS3R primers. [ABSTRACT FROM AUTHOR]

A simple procedure is elaborated for the preparation of cyclic enol ethers by Ni-catalyzed cyclization of halogenated alcohols. [ABSTRACT FROM AUTHOR]

The use of Bpin2 as the reductant, NaOtBu as base, and CuCl/phen as catalyst system permits an interesting defluorinative coupling of trifluoromethylketones with aldehydes to give moderate to good yields of α,α-difluoro-β-hydroxyketones. [ABSTRACT FROM AUTHOR]

The synthesis of a novel fluorinated nickel enolate (FNE) is developed and the utility of this species as catalyst for the homo-dimerization of aldehydes to esters is demonstrated. [ABSTRACT FROM AUTHOR]

The article presents chemical equations related to the article "Palladium-Catalyzed Coupling Reaction of Perfluoroarenes with Diarylzinc Compounds" by M. Ohashi and others, published in the "Chemistry: A European Journal" in 2014.

We have synthesized a new nickel enolate [(PhCOCF2)Ni(dcpe)][FB(C6F5)3] featuring fluorine atoms on the enolate moiety via B(C6F5)3-promoted C-F bond activation of α,α,α-trifluoroacetophenone. X-ray diffraction study of [(PhCOCF2)Ni(dcpe)][FB(C6F5)3] revealed that the complex had adopted an η(3)-oxallyl coordination mode in the crystal lattice. The reaction of (t)BuNC with [(PhCOCF2)Ni(dcpe)][FB(C6F5)3] resulted in the coordination of isocyanide to the nickel center to form a C-bound enolate complex. The reactions of [(PhCOCF2)Ni(dcpe)][FB(C6F5)3] with aldehydes gave insertion products quantitatively which were fully characterized by NMR spectroscopy. Furthermore, we established unique catalytic applications for [(PhCOCF2)Ni(dcpe)][FB(C6F5)3] toward a Tishchenko reaction, along with a highly selective crossed-esterification of α,α,α-trifluoroacetophenones with aldehydes.

Organofluorine compounds are widely used in all aspects of the chemical industry. Although tetrafluoroethylene (TFE) is an example of an economical bulk organofluorine feedstock, the use of TFE is mostly limited to the production of poly(tetrafluoroethylene) and copolymers with other alkenes. Furthermore, no catalytic transformation of TFE that involves carbon-fluorine bond activation has been reported to date. We herein report the first example of a palladium-catalyzed coupling reaction of TFE with arylzinc reagents in the presence of lithium iodide, giving α,β,β-trifluorostyrene derivatives in excellent yields.