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Fluoroaromatics from arylamines, a convenient one-pot conversion using nitrosonium tetrafluoroborate
A simple, novel and extremely versatile procedure has been identified for the conversion of arylamines into the corresponding arylfluorides. The amine is treated with nitrosonium tetrafluoroborate in dichloromethane and the resulting diazonium tetrafluoroborate is heated, without isolation or drying, to give the fluoroaromatic, generally in good yield. The method is applicable even to arylamines bearing carboxyl and hydroxyl substituents which give poor yields of arylfluorides under Balz-Schiemann conditions.
Milner
p. 73 - 82
(1992)
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Cleavage of Aryl-Tin Bonds with Elemental Fluorine: Rapid Synthesis of Fluorobenzene
Fluorobenzene has been synthesized rapidly by treatment of aryltin derivatives with F2 in CFCl3 or CCl4 at -78 to 0 deg C.
Adam, Michael J.,Pate, Brian D.,Ruth, Thomas J.,Berry, Joffre M.,Hall, Laurance D.
p. 733
(1981)
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DIRECT LIQUID-PHASE FLUORINATION OF AROMATIC COMPOUNDS. NEW ADVANCES IN ELECTROPHILIC FLUORINATION
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Gambaretto, G. P.,Conte, L.,Fraccaro, C.,Napoli, M.
p. 241
(1991)
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Activation of Aryl Halides by Nickel(I) Pincer Complexes: Reaction Pathways of Stoichiometric and Catalytic Dehalogenations
Homolytic C-X bond cleavage of organohalides by the T-shaped nickel(I) complexes [LigNiI] 1 bearing the iso-PyrrMeBox ligand had been found previously to be the crucial activation step in the asymmetric hydrodehalogenation of geminal dihalides. Here, this mechanistic investigation is extended to aryl halides, which allowed a systematic study of the activation process by a combination of experimental data and density functional theory modeling. While the activation of both aryl chlorides and geminal dichlorides appears to proceed via an analogous transition state, the generation of a highly stabile nickel(II)aryl species in the reaction of the aryl chlorides for the former represents a major difference in the reactive behavior. This difference was found to have a crucial impact on the activity of these nickel pincer systems as catalysts in the dehalogenation of aryl chlorides compared to geminal dichlorides and highlights the importance of the regulatory pathways controlling the nickel(I) concentration throughout the catalysis. These results along with the identification and characterization of novel nickel(II)aryl species are presented.
Rettenmeier, Christoph A.,Wenz, Jan,Wadepohl, Hubert,Gade, Lutz H.
p. 8214 - 8224
(2016)
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Preparation of Fluoroarenes in One-Pot Diazotization and Fluoro-Dediazoniation of Aminoarenes Using HF or HF-Base. The Functions of Bases in the HF Solution
In a one-pot diazotization of anilines followed by fluoro-dediazoniation in situ using HF or HF with bases (HF-Base) as a solvent, the diazotization stage has been found to play the most important part to yield fluoroarenes effectively.Diazotization of anilines was greatly influenced by the composition of the HF solution, and greatly enhanced by employing appropriate amounts of bases, such as pyridine.On the other hand, fluoro-dediazoniation of diazonium salts, once formed, took place very readily in HF or HF-Base to produce fluoroarenes in high yield, although such bases served to slow down the rate of decomposition of diazonium salts to some extent.
Fukuhara, Tsuyoshi,Sasaki, Satoshi,Yoneda, Norihiko,Suzuki, Akira
p. 2058 - 2062
(1990)
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Feng,Mamula
p. 507
(1958)
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Energy Disposal in Gas-phase Nucleophilic Displacement Reactions
The partitioning of reaction exothermicity into relative translational energy of the products of gas-phase SN2 (F- + CH3Cl) and nucleophilic aromatic substitution F- + C6H5Cl) reactions has been investigated using kinetic energy release Fourier transform ion cyclotron resonance spectroscopy.The chloride product ion is observed to be highly translationally excited for the Sn2 reaction, indicating a cold internal energy distribution for the products.For the chlorobenzene reaction the products are not generated with large translational energies.The results are compa red with a statistical model.Ion-intensity profiles for the CH3Cl reaction deviate significantly from the statistical model whereas the chlorobenzene results are consistent with this model.The kinetic energy release for the CH3Cl reaction is compared with energy-diposal results for the photodissociation and dissociative electron-attachment processes of halomethanes.In all three cases a node in the molecular orbital between the carbon atom and the departing halogen results in a repulsive energy release.Ion-retention curves for the nucleophilic aromatic substitution reaction are consistent with the existence of a long-lived ion-dipole complex on the exit channel for this reaction.
VanOrden, Steven L.,Pope, R. Marshall,Buckner, Steven W.
p. 1003 - 1007
(1991)
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Taming the Lewis Superacidity of Non-Planar Boranes: C?H Bond Activation and Non-Classical Binding Modes at Boron
The rational design of a geometrically constrained boron Lewis superacid featuring exceptional structure and reactivity is disclosed. It enabled the formation of non-classical electron deficient B?H?B type of bonding, which was supported by spectroscopic and structural parameters as well as computational studies. Taming the pyramidal Lewis acid electrophilicity through weak coordinating anion dissociation enabled a series of highly challenging chemical transformations, such as Csp2?H and Csp3?H activation under a frustrated Lewis pair regime and the cleavage of Csp3?Si bonds. The demonstration of such rich chemical behaviour and flexibility on a single molecular compound makes it a unique mediator of chemical transformations generally restricted to transition metals.
Berionni, Guillaume,Champagne, Beno?t,Chardon, Aurélien,Fusaro, Luca,Mahaut, Damien,Osi, Arnaud,Tumanov, Nikolay,Wouters, Johan
supporting information

(2022/01/20)

Photochemical Sandmeyer-type Halogenation of Arenediazonium Salts
Trihalide salts were found to efficiently promote photochemical dediazotizing halogenations of diazonium salts. In contrast to classical Sandmeyer reactions, no metal catalysts are required to achieve high yields and outstanding selectivities for halogena
Belitz, Florian,Goo?en, Lukas J.,Manu Martínez, ángel,Schmid, Rochus,Sivendran, Nardana,Sowa Prendes, Daniel
(2022/01/19)

Process for Preparing Fluorobenzene by Direct Fluorination
The invention relates to a use of a fluorination gas, wherein the elemental fluorine (F2) is present in a high concentration, for example, in a concentration of elemental fluorine (F2), especially of equal to much higher than 15% or even 20% by volume (i.e., at least 15% or even 20% by volume), and to a process for the manufacture of a fluorinated benzene by direct fluorination employing a fluorination gas, wherein the elemental fluorine (F2) is present in a high concentration. The process of the invention is directed to the manufacture of a fluorinated benzene by direct fluorination. Especially the invention is of interest in the preparation of fluorinated benzene, final products and as well intermediates, for usage in agro-, pharma-, electronics-, catalyst, solvent and other functional chemical applications. The fluorination process of the invention may be performed batch-wise or in a continuous manner. If the process of the invention is performed batch-wise, a column (tower) reactor may be used. If the process of the invention is continuous a microreactor may be used. The invention is characterized in that the starting compound is benzene, and the fluorinated compound produced is a fluorinated benzene, preferably monofluorobenzene.
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Paragraph 0176-0184

(2021/02/26)

Mechanistic studies into visible light-driven carboxylation of aryl halides/triflates by the combined use of palladium and photoredox catalysts
The reaction mechanism of palladium-catalyzed visible light-driven carboxylation of aryl halides and triflates with a photoredox catalyst was examined in detail. Experimental and theoretical studies indicated that the active species for photoredox- catalyzed reduction was cationic ArPd(II)+ species to generate nucleophilic ArPd(I) or its further reduced ArPd(0)- species, which reacted with CO2 to give carboxylic acids. Hydrodehalogenated compounds, main byproducts in this carboxylation, were thought to be generated by protonation of these reduced species.
Caner, Joaquim,Iwasawa, Nobuharu,Martin, Ruben,Murata, Kei,Shimomaki, Katsuya,Toriumi, Naoyuki
supporting information
p. 1846 - 1853
(2021/08/13)

Full continuous flow synthesis process of fluorine-containing aromatic hydrocarbon compounds
The invention provides a full continuous flow synthesis process of a fluorine-containing aromatic hydrocarbon compound, and belongs to the technical field of preparation of halogenated hydrocarbon carbocyclic organic compounds. Arylamine and hydrogen fluoride are pumped into a thermostat A and a thermostat B respectively and flow into a micro-channel reactor C for a salt forming reaction after constant temperature treatment, and a sulfuric acid solution of nitrosyl sulfuric acid is pumped into a thermostat D and flows into a micro-channel reactor E together with a salt forming product flowing out of the micro-channel reactor C for a diazotization reaction after constant temperature treatment. A product flows into a micro-channel reactor F to be subjected to a thermal decomposition reaction, is cooled by a cooler G and then enters a three-phase separator H to be continuously separated, nitrogen is discharged after being subjected to spraying deacidification, a fluorine-containing aromatic hydrocarbon crude product is subjected to continuous alkali washing, continuous drying and continuous rectification to obtain a fluorine-containing aromatic hydrocarbon finished product, and a hydrofluoric acid and sulfuric acid mixture is subjected to continuous distillation to obtain a product. The hydrogen fluoride and sulfuric acid are obtained. The full continuous flow synthesis process has the advantages of high reaction yield, excellent product quality, good production safety, less pollutant discharge and the like.
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Paragraph 0067-0080; 0137-0163

(2021/04/07)

Radical Decarboxylative Carbometalation of Benzoic Acids: A Solution to Aromatic Decarboxylative Fluorination
Abundant aromatic carboxylic acids exist in great structural diversity from nature and synthesis. To date, the synthetically valuable decarboxylative functionalization of benzoic acids is realized mainly by transition-metal-catalyzed decarboxylative cross couplings. However, the high activation barrier for thermal decarboxylative carbometalation that often requires 140 °C reaction temperature limits both the substrate scope as well as the scope of suitable reactions that can sustain such conditions. Numerous reactions, for example, decarboxylative fluorination that is well developed for aliphatic carboxylic acids, are out of reach for the aromatic counterparts with current reaction chemistry. Here, we report a conceptually different approach through a low-barrier photoinduced ligand to metal charge transfer (LMCT)-enabled radical decarboxylative carbometalation strategy, which generates a putative high-valent arylcopper(III) complex, from which versatile facile reductive eliminations can occur. We demonstrate the suitability of our new approach to address previously unrealized general decarboxylative fluorination of benzoic acids.
Xu, Peng,López-Rojas, Priscila,Ritter, Tobias
supporting information
p. 5349 - 5354
(2021/05/05)

Heterogeneously Catalyzed Selective Decarbonylation of Aldehydes by CeO2-Supported Highly Dispersed Non-Electron-Rich Ni(0) Nanospecies
Aldehyde decarbonylation has been extensively investigated, primarily using noble-metal catalysts; however, nonprecious-base-metal-catalyzed aldehyde decarbonylation has been hardly reported. We have established an efficient selective aldehyde decarbonylation reaction with a broad substrate scope and functional group tolerance utilizing a heterogeneous Ni(0) nanospecies catalyst supported on CeO2. The high catalytic performance is attributable to the highly dispersed and non-electron-rich Ni(0) nanospecies, which possibly suppress a side reaction producing esters and adsorbed CO-derived inhibition of the catalytic turnover, according to detailed catalyst characterization and kinetic evaluation.
Matsuyama, Takehiro,Yatabe, Takafumi,Yabe, Tomohiro,Yamaguchi, Kazuya
p. 13745 - 13751
(2021/11/17)

Process for Preparing Fluorobenzene and Benzoic Acid Hypofluorite
The invention relates to a use of a fluorination gas, the elemental fluorine (F2) is preferably present in a high concentration, e.g. in a concentration of elemental fluorine (F2), especially of equal to much higher than 15% or even 20% by volume (i.e., at least 15% or even 20% by volume), and to a process for the manufacture of a fluorinated benzene starting from benzoic acid by direct fluorination employing a fluorination gas. The elemental fluorine (F2) is preferably present in high concentration, and subsequent decarboxylation of the benzoic acid hypofluorite obtained by direct fluorination. The process of the invention is also directed to the manufacture of benzoic acid hypofluorite by direct fluorination of benzoic acid. Especially the invention is of interest in the preparation of fluorinatedbenzene, final products and as well intermediates, for usage in agro-, pharma-, electronics-, catalyst, solvent and other functional chemical applications.
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Paragraph 0214-0215; 0224-0237

(2021/03/05)

Boronic Acid Pairs for Sequential Bioconjugation
Boronic acids can play diverse roles when applied in biological environments, and employing boronic acid structures in tandem could provide new tools for multifunctional probes. This Letter describes a pair of boronic acid functional groups, 2-nitro-arylboronic acid (NAB) and (E)-alkenylboronic acid (EAB), that enable sequential cross-coupling through stepwise nickel- and copper-catalyzed processes. The selective coupling of NAB groups enables the preparation of stapled peptides, protein-protein conjugates, and other bioconjugates.
Ball, Zachary T.,Ding, Yuxuan,Miller, Mary K.,Swierczynski, Michael J.
supporting information
p. 5334 - 5338
(2021/07/26)

Metal-Free Photoredox-Catalyzed Hydrodefluorination of Fluoroarenes Utilizing Amide Solvent as Reductant
A metal-free photoredox-catalyzed hydrodefluorination of fluoroarenes was achieved by using N,N,N’,N’-tetramethyl-para-phenylenediamine (1) as a strong photoreduction catalyst. This reaction was applicable not only to electron-rich monofluoroarenes but also to polyfluoroarenes to afford non-fluorinated arenes. The experimental mechanistic studies indicated that the amide solvent NMP plays an important role for regeneration of the photocatalyst, enabling additive-free photoreduction catalysis.
Toriumi, Naoyuki,Yamashita, Kazuya,Iwasawa, Nobuharu
supporting information
p. 12635 - 12641
(2021/08/03)

Vinyl Thianthrenium Tetrafluoroborate: A Practical and Versatile Vinylating Reagent Made from Ethylene
The use of vinyl electrophiles in synthesis has been hampered by the lack of access to a suitable reagent that is practical and of appropriate reactivity. In this work we introduce a vinyl thianthrenium salt as an effective vinylating reagent. The bench-stable, crystalline reagent can be readily prepared from ethylene gas at atmospheric pressure in one step and is broadly useful in the annulation chemistry of (hetero)cycles, N-vinylation of heterocyclic compounds, and palladium-catalyzed cross-coupling reactions. The structural features of the thianthrene core enable a distinct synthesis and reactivity profile, unprecedented for other vinyl sulfonium derivatives.
Juliá, Fabio,Paulus, Fritz,Ritter, Tobias,Yan, Jiyao
supporting information
p. 12992 - 12998
(2021/09/03)

Decarboxylative Hydroxylation of Benzoic Acids
Herein, we report the first decarboxylative hydroxylation to synthesize phenols from benzoic acids at 35 °C via photoinduced ligand-to-metal charge transfer (LMCT)-enabled radical decarboxylative carbometalation. The aromatic decarboxylative hydroxylation is synthetically promising due to its mild conditions, broad substrate scope, and late-stage applications.
Ritter, Tobias,Su, Wanqi,Xu, Peng
supporting information
p. 24012 - 24017
(2021/10/06)

Novel manufacturing method of fluoro-aryl compounds and derivatives thereof
The invention relates to a novel method of manufacturing fluoro-aryl compounds and derivatives thereof, in particular, fluorobenzene and derivatives thereof. The production environment of the manufacturing method is environmentally friendly. The shortages of a conventional method are overcome through a simple and beneficial mode. Compared with the prior art, the provided method is more effective,more environmentally friendly, and more energy saving. The method is used to produce core fluorinated aromatic compounds, preferably, core fluorinated fluorobenzene. On one aspect, the invention provides a method, which is advantages in industry and uses HF and a halogenated benzene precursor to prepare fluorobenzene and hydrogen halide. Moreover, the invention provides chlorobenzene as the primary raw material to prepare fluorobenzene, which is an important material in industry, and a beneficial, unexpected and simple application of chlorobenzene. In the prior art, the provided application ofchlorobenzene is unknown.
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Paragraph 0201-0205

(2020/01/25)

Process for preparing fluorobenzene and catalyst thereof
The present invention relates to a process for the manufacture or preparation of fluorobenzene, in particular fluorobenzene, in a vapour phase fluorination process. For example, the process of the present invention may comprise the batch or continuous production or production of fluorobenzene, in particular monofluorobenzene, using gaseous hydrogen fluoride (HF) as a fluorination gas. Likewise, inthe process of the invention, for example, a fluorination catalyst is involved.
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Paragraph 0106; 0112; 0119-0124; 0132-0164

(2020/05/30)

Novel process for producing phenyl fluoride, diphenyl ketone fluoride, and derivatives thereof
The invention relates to a novel process for producing phenyl fluoride, diphenyl ketone fluoride, and derivatives thereof, especially the phenyl fluoride and derivatives thereof. The invention especially relates to a novel environment-friendly process for synthesizing phenyl fluoride and diphenyl ketone fluoride, which are the raw materials for preparing polyaryl-ether-ketone PAEK. The invention discloses the method that is more effective and environment-friendly for preparing the compounds through a Friedel-Crafts reaction, and further a more environment-friendly process, and provdies beneficial catalysts. Another object of the present invention is to employ the Friedel-Crafts reaction and adopts the beneficial catalysts, wherein the catalyst can be easily combined with the fluoridation reaction which can be carried out before, or after the Friedel-Crafts reaction. Herein, another object of the invention is to use the catalyst in the Friedel-Crafts reaction, wherein the catalyst can work in both the Friedel-Crafts reaction and the fluoridation reaction.
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Paragraph 0285-0288

(2020/07/02)

Pd nanoparticles supported on amphiphilic porous organic polymer as an efficient catalyst for aqueous hydrodechlorination and Suzuki-Miyaura coupling reactions
Developing efficient and recyclable heterogeneous catalysts for organic reactions in water is important for the sustainable development of chemical industry. In this work, Pd nanoparticles supported on DABCO-functionalized porous organic polymer was successfully prepared through an easy copolymerization and successive immobilization method. Characterization results indicated that the prepared catalyst featured big surface area, hierarchical porous structure, and excellent surface amphiphilicity. We demonstrated the use of this amphiphilic catalyst in two case reactions, i.e. the aqueous hydrodechlorination and Suzuki-Miyaura coupling reactions. Under mild reaction conditions, the catalyst showed high catalytic activities for the two reactions. In addition, the catalyst could be easily recovered and reused for several times. Also, no obvious Pd leaching and aggregation of Pd nanoparticles occurred up during the consecutive reactions.
Lei, Yizhu,Zhu, Wenchao,Wan, Yali,Wang, Renshu,Liu, Hailong
(2019/12/15)

Catalytic Hydrogenolysis of Aryl C-F Bonds Using a Bimetallic Rhodium-Indium Complex
A homogeneous rhodium-indium catalyst hydrodefluorinates substrates bearing strong aryl C-F bonds, including difluoro- and fluorobenzene, using 1 atm of H2, alkoxide bases, and moderate temperatures (70-90 °C). Characterization of catalytic intermediates establishes a formal Rh-I/RhI redox cycle. The Rh → In interaction is proposed to enable catalysis by stabilizing the reactive Rh-I species, which is responsible for cleaving the Ar-F bond and is ultimately regenerated using H2 and base.
Moore, James T.,Lu, Connie C.
supporting information
p. 11641 - 11646
(2020/07/27)

Photoredox catalysis with aryl sulfonium salts enables site-selective late-stage fluorination
Photoredox catalysis, especially in combination with transition metal catalysis, can produce redox states of transition metal catalysts to facilitate challenging bond formations that are not readily accessible in conventional redox catalysis. For arene functionalization, metallophotoredox catalysis has successfully made use of the same leaving groups as those valuable in conventional cross-coupling catalysis, such as bromide. Yet the redox potentials of common photoredox catalysts are not sufficient to reduce most aryl bromides, so synthetically useful aryl radicals are often not directly available. Therefore, the development of a distinct leaving group more appropriately matched in redox potential could enable new reactivity manifolds for metallophotoredox catalysis, especially if arylcopper(iii) complexes are accessible, from which the most challenging bond-forming reactions can occur. Here we show the conceptual advantages of aryl thianthrenium salts for metallophotoredox catalysis, and their utility in site-selective late-stage aromatic fluorination.
Li, Jiakun,Chen, Junting,Sang, Ruocheng,Ham, Won-Seok,Plutschack, Matthew B.,Berger, Florian,Chabbra, Sonia,Schnegg, Alexander,Genicot, Christophe,Ritter, Tobias
p. 56 - 62
(2019/11/28)

Fluorination of arylboronic esters enabled by bismuth redox catalysis
Bismuth catalysis has traditionally relied on the Lewis acidic properties of the element in a fixed oxidation state. In this paper, we report a series of bismuth complexes that can undergo oxidative addition, reductive elimination, and transmetallation in a manner akin to transition metals. Rational ligand optimization featuring a sulfoximine moiety produced an active catalyst for the fluorination of aryl boronic esters through a bismuth (III)/bismuth (V) redox cycle. Crystallographic characterization of the different bismuth species involved, together with a mechanistic investigation of the carbonfluorine bond-forming event, identified the crucial features that were combined to implement the full catalytic cycle.
Planas, Oriol,Wang, Feng,Leutzsch, Markus,Cornella, Josep
p. 313 - 317
(2020/01/28)

Silylation of Aryl Chlorides by Bimetallic Catalysis of Palladium and Gold on Alloy Nanoparticles
Supported palladium-gold alloy-catalyzed cross-coupling of aryl chlorides and hydrosilanes enabled the selective formation of aryl-silicon bonds. Whereas a monometallic palladium catalyst predominantly promoted the hydrodechlorination of aryl chlorides and gold nanoparticles showed no catalytic activity, gold-rich palladium-gold alloy nanoparticles efficiently catalyzed the title reaction to give arylsilanes with high selectivity. A wide array of aryl chlorides and hydrosilanes participated in the heterogeneously-catalyzed reaction to furnish the corresponding arylsilanes in 34–80% yields. A detailed mechanistic investigation revealed that palladium and gold atoms on the surface of alloy nanoparticles independently functioned as active sites for the formation of aryl nucleophiles and silyl electrophiles, respectively, which indicates that palladium and gold atoms on alloy nanoparticles work together to enable the selective formation of aryl-silicon bonds. (Figure presented.).
Miura, Hiroki,Masaki, Yosuke,Fukuta, Yohei,Shishido, Tetsuya
supporting information
p. 2642 - 2650
(2020/04/22)

Tailored quinones support high-turnover Pd catalysts for oxidative C-H arylation with O2
Palladium(II)-catalyzed carbon-hydrogen (C-H) oxidation reactions could streamline the synthesis of pharmaceuticals, agrochemicals, and other complex organic molecules. Existing methods, however, commonly exhibit poor catalyst performance with high palladium (Pd) loading (e.g., 10 mole %) and a need for (super)stoichiometric quantities of undesirable oxidants, such as benzoquinone and silver(I) salts. The present study probes the mechanism of a representative Pd-catalyzed oxidative C-H arylation reaction and elucidates mechanistic features that undermine catalyst performance, including substrate-consuming side reactions and sequestration of the catalyst as an inactive species. Systematic tuning of the quinone cocatalyst overcomes these deleterious features. Use of 2,5-di-tert-butyl-p-benzoquinone enables efficient use of molecular oxygen as the oxidant, high reaction yields, and >1900 turnovers by the Pd catalyst.
Salazar, Chase A.,Flesch, Kaylin N.,Haines, Brandon E.,Zhou, Philip S.,Musaev, Djamaladdin G.,Stahl, Shannon S.
p. 1454 - 1460
(2021/01/14)

Aryl dechlorination and defluorination with an organic super-photoreductant
Direct excitation of the commercially available super-electron donor tetrakis(dimethylamino)ethylene (TDAE) with light-emitting diodes at 440 or 390 nm provides a stoichiometric reductant that is able to reduce aryl chlorides and fluorides. The method is very simple and requires only TDAE, substrate, and solvent at room temperature. The photoactive excited state of TDAE has a lifetime of 17.3 ns in cyclohexane at room temperature and an oxidation potential of ca. -3.4 V vs. SCE. This makes TDAE one of the strongest photoreductants able to operate on the basis of single excitation with visible photons. Direct substrate activation occurs in benzene, but acetone is reduced by photoexcited TDAE and substrate reduction takes place by a previously unexplored solvent radical anion mechanism. Our work shows that solvent can have a leveling effect on the photochemically available redox power, reminiscent of the pH-leveling effect that solvent has in acid-base chemistry.
Glaser, Felix,Kerzig, Christoph,Larsen, Christopher B.,Wenger, Oliver S.
p. 1035 - 1041
(2020/08/28)

Decarboxylative Conjunctive Cross-coupling of Vinyl Boronic Esters using Metallaphotoredox Catalysis
The synthesis of complex alkyl boronic esters through conjunctive cross-coupling of vinyl boronic esters with carboxylic acids and aryl iodides is described. The reaction proceeds under mild metallaphotoredox conditions and involves an unprecedented decarboxylative radical addition/cross-coupling cascade of vinyl boronic esters. Excellent functional-group tolerance is displayed, and application of a range of carboxylic acids, including secondary α-amino acids, and aryl iodides provides efficient access to highly functionalized alkyl boronic esters. The decarboxylative conjunctive cross-coupling was also applied to the synthesis of sedum alkaloids.
Aggarwal, Varinder K.,Duong, Vincent K.,Mega, Riccardo S.,Noble, Adam
supporting information
p. 4375 - 4379
(2020/02/11)

A Nickel-Doped Dehydrobenzoannulene-Based Two-Dimensional Covalent Organic Framework for the Reductive Cleavage of Inert Aryl C-S Bonds
The development of metalated covalent organic frameworks (COFs) is useful for generating recyclable catalytic systems for practical applications. Herein, we report the synthesis, characterization, and catalytic properties of an azine-linked two-dimensional (2D) COF containing nickel-doped dehydrobenzoannulene (DBA) units. We demonstrate that Ni-DBA-2D-COF can be used to reductively cleave the aryl C-S bonds of several organosulfur compounds utilizing dimethylethylsilane as the reducing agent. The Ni-DBA-2D-COF catalytic system displays excellent recyclability and good yields. This work highlights a rare example of utilizing metalated DBA complexes to perform catalytic transformations.
Haug, W. Karl,McGrier, Psaras L.,Morman, Blake T.,Thomas, Christine M.,Wolfson, Eric R.
supporting information
p. 5521 - 5525
(2020/04/09)

The Electronic Properties of Ni(PNN) Pincer Complexes Modulate Activity in Catalytic Hydrodehalogenation Reactions
Three chloronickel(II) complexes of PNN- pincer ligands with pyrazolyl and diphenylphosphino donors appended to different arms of diarylamido anchors were prepared and fully characterized. The three derivatives (1-OMe, 1-Me, 1-CF3) differ only by the identity of the para-aryl substituent on the pyrazolyl arm with 1-OMe being 310 mV easier to oxidize than 1-CF3. All three complexes are competent catalysts for hydrodehalogenation reactions of 1-bromooctane and a variety of aryl halides in dimethylacetamide using NaBH4 as both base and hydride source. Comparative studies using diverse substrates showed that catalytic activity correlates with electron donor properties; 1-OMe was superior to the other two. Deuterium labeling studies verified NaBD4 as the deuteride source and excluded solvent-assisted radical pathways.
Wang, Denan,Gardinier, James R.
p. 4425 - 4434
(2020/10/19)

Hydrogen bonding promoted simple and clean photo-induced reduction of C-X bond with isopropanol
We herein report a simple and clean photo-induced metal-free reduction of C-X bond under an atmosphere of air at room temperature. Isopropanol is used as both the reducing reagent and solvent. Various functional groups (acids, esters, alcohols, anilines, phenols, indoles, pyridines, cyano and trifluoromethyl groups) and other heterocyclic compounds are tolerated. Different organic halides (including C-I, C-Br and C-Cl bonds) can be dehalogenated with moderate to excellent yields. Polyhalides are also reduced chemoselectively and efficiently. DFT calculation suggests a six-membered ring transition state via C-X H-O hydrogen bonding to decrease the activation energy.
Cao, Dawei,Yan, Chaoxian,Zhou, Panpan,Zeng, Huiying,Li, Chao-Jun
supporting information
p. 767 - 770
(2019/01/21)

Involving Single-Atom Silver(0) in Selective Dehalogenation by AgF under Visible-Light Irradiation
The dehalogenation-arylation and the hydrodehalogenation of various types of organic halides are selectively realized using AgF and visible light without any organic additives under mild conditions. Single-atom silver(0) (denoted as SAAg) serves as the catalytically active center, and the TOF of SAAg reaches 6000 h-1. This elusive activity of Ag is beyond that expected from its ionic, nano, or bulk forms.
Wu, Wenli,Cui, Enxin,Zhang, Yun,Zhang, Chen,Zhu, Feng,Tung, Chen-Ho,Wang, Yifeng
p. 6335 - 6341
(2019/07/04)

Competing dehalogenation versus borylation of aryl iodides and bromides under transition-metal-free basic conditions
In this work, selectivity-controllable base-promoted transition-metal-free borylation and dehalogenation of aryl halides are described. Under the conditions of borylation, the dehalogenation which emerges as a competitive side reaction has been well-controlled by carefully controlling the borylation conditions. On the other hand, the dehalogenation using benzaldehyde as a hydrogen source has also been accomplished. The applications of direct radical borylation and dehalogenation of aryl halides demonstrate their synthetic practicability in pharmaceutical-oriented organic synthesis. Based on the experimental evidences, the tBuOK/1,10-Phen-triggered radical nature of both competitive reactions has been revealed.
Niu, Yi-Jie,Sui, Guo-Hui,Zheng, Hong-Xing,Shan, Xiang-Huan,Tie, Lin,Fu, Jia-Le,Qu, Jian-Ping,Kang, Yan-Biao
p. 10805 - 10813
(2019/09/30)

The linkage between reversible Friedel–Crafts acyl rearrangements and the Scholl reaction
Friedel–Crafts acyl rearrangements in PPA (at 80–240?°C) and Scholl reactions in AlCl3/NaCl (at 140–220?°C) of benzoylnaphthalenes and fluorobenzoylnaphthalenes have been studied experimentally as a function of temperature and time and computationally. 1BzNA, 2BzNA, 1-4FBzNA, 2-4FBzNA, 1-3FBzNA, 2-3FBzNA, 1-2FBzNA, and 2-2FBzNA were synthesized by classical Friedel–Crafts acylations of naphthalene with benzoyl chloride, benzene with 2-naphthoyl chloride,?fluorobenzene with 1- and 2-naphthoyl chlorides and of naphthalene with fluorobenzoyl chlorides, and served as substrates in the investigation. Their structures have been determined by X-ray crystallography and verified by their 1H-, 13C-, and 19F-NMR spectra. 1BzNA, 1-4FBzNA, 1-3FBzNA, and 2-2FBzNA crystallized as the E-diastereomers, whereas 2BzAN, 1-2FBzAN, 2-4FBzAN, and 2-3FBzAN crystallized as the Z-diastereomers. The deviations of the carbonyl group from the naphthyl plane were higher as compared with the deviations from the phenyl plane and were considerably higher in the α-naphthyl ketones than in the β-naphthyl ketones. Intermolecular interactions due to C–H···O and/or C–H···F contacts in the crystal structures of 1E-4FBzNA and 1E1′E-3FBzAN have been revealed. 1BzNA rearranged in PPA under argon to 2BzNA via deacylation to naphthalene (e.g., 140?°C, 10?h) and underwent a regioselective intramolecular cyclodehydrogenation at high temperatures to the Scholl reaction product 7H-benz[de]anthracen-7-one (BdeAN) (e.g., 200?°C, 6?h). At 80?°C, benzene was isolated. 2BzNA underwent in PPA deacylation to naphthalene (e.g., 160?°C, 6?h) and an intramolecular cyclodehydrogenation to BdeAN at high temperatures (e.g., 220?°C, 6?h), necessarily via the putative intermediate 1BzNA. Higher yields of the acyl rearrangement and the Scholl reaction products were obtained under oxygen. 1-4FBzNA and 2-4FBzNA reacted in PPA analogously to 1BzNA and 2BzNA, respectively, with the following exceptions: 2-4FBzNA underwent an acyl rearrangement in PPA to 1-4FBzNA at 260–300?°C, without any formation of the Scholl reaction product 10FBdeAN. 1-4FBzNA also did not yield 10FBdeAN. 1-2FBzNA and 2-2FBzNA behaved similarly. The formation of naphthalene and benzene in the deacylation steps indicated cleavages of both the 1- and 2-naphthyl–benzoyl bonds and the 1- and 2-naphthoyl–phenyl bonds to give naphthalene and benzoylium cation and benzene and 1- and 2-naphthoylium cation, respectively. At 80–100?°C, 1-2FBzNA, 1-3FBzNA, and 1-4FBzNA underwent deacylations to fluorobenzene in PPA, followed by reacylation, each giving a mixture of the three 1-fluorobenzoylnaphthalenes. 2FBzNA, 2-3FBzNA, and 2-4FBzNA behaved similarly, each giving a mixture of the three 2-fluorobenzoylnaphthalenes. The results taken together verified the reversibility of the 1-BzNA?2BzNA acyl rearrangements in PPA. The Scholl reaction (AlCl3/NaCl) of 1BzNA (e.g., at 140?°C) gave BdeAN and 2BzNA, whereas 2BzNA gave only BdeAN (at 200–220?°C). 1-4FBzNA and 2-4FBzNA gave (at 200–220?°C) only 2-4FBzNA and 1-4FBzNA, respectively. All the six FBzNA isomers failed to undergo Scholl reaction cyclodehydrogenations to give any FBdeAN isomer. A linkage between the Friedel–Crafts acyl rearrangements and the Scholl reaction has thus been established. A systematic DFT study at B3LYP/6-311(d,p)/PCM (formic acid)) substantiated the predicted mechanism and the reversibility of the acyl rearrangements of benzoylnaphthalenes, in which 1BzNA and 2BzNA are the kinetically controlled and the thermodynamically controlled products, respectively. The DFT-calculated Gibbs free-energy of the transition-state (1Z-1BzNH+ ?? 2σ-2BzNA) in the Friedel–Crafts acyl rearrangement of 1Z-BzNA is considerably lower than the transition state of the cyclization step in the arenium-cation mechanism of the Scholl reaction, in line with experiment, which indicated higher temperatures for the Scholl reaction. DFT calculations of the dication pathway of the Scholl reaction of the E- and Z-diastereomers/conformers of 1BzNA confirmed the preference of the formation of BdeAN versus BaFL, consistently with experiment.
Agranat, Israel,Oded, Yaacov Netanel,Mala’bi, Tahani,Pogodin, Sergey,Cohen, Shmuel
p. 1579 - 1610
(2019/07/29)

Ni: Vs. Pd in Suzuki-Miyaura sp2-sp2 cross-coupling: A head-to-head study in a comparable precatalyst/ligand system
The Suzuki-Miyaura reaction is a cornerstone method for sp2-sp2 cross-coupling in industry. There has been a concerted effort to enable the use of Ni catalysis as an alternative to Pd in order to mitigate cost and improve sustainability. Despite significant advances, ligand development for Ni-catalyzed Suzuki-Miyaura cross-coupling remains underdeveloped when compared to Pd and, as a consequence, ligands for Ni-catalyzed processes are typically taken from the Pd arena. In this study we evaluate the effect of using a similar Ni and Pd precatalyst based on a common bidentate ligand (dppf) in a head-to-head format for the most common type of biaryl couplings, establishing the practical implications of direct replacement of Pd with Ni, and identifying the potential origins of these observations in a mechanistic context.
West, Matthew J.,Watson, Allan J. B.
supporting information
p. 5055 - 5059
(2019/06/03)

Nickel-catalysed C–O bond reduction of 2,4,6-triaryloxy-1,3,5-triazines in 2-methyltetrahydrofuran
A nickel-catalysed reduction of phenol derivatives activated by 2,4,6-trichloro-1,3,5-triazine (TCT) in ecofriendly 2-methyltetrahydrofuran (2-MeTHF) is described. The phenol-TCT derivatives were readily prepared using grinding method in short time without further purification. This catalytic system allowed the facile C–O cleavage of phenol-TCT derivatives under mild reaction conditions with high efficiency and good functional group tolerance. Gram-scale reaction was also achieved. Particularly, sequential functionalization of phenol-TCT derivatives followed by C–O bond reduction could also be realized, affording the high value-added products in moderate to good yields.
Wang, Yaoyao,Shen, Jun,Chen, Qun,Wang, Liang,He, Mingyang
p. 409 - 412
(2018/10/02)

Chemoselective Hydrodeoxygenation of Carboxylic Acids to Hydrocarbons over Nitrogen-Doped Carbon-Alumina Hybrid Supported Iron Catalysts
The establishment of catalyst systems for the chemoselective hydrodeoxygenation (HDO) of carboxylic acids to hydrocarbons, such as the HDO of long-chain fatty acids to alkanes, is important for biomass to biofuel conversion. As the most abundant and probably the cheapest transition metal on the earth, iron is a promising non-noble-metal alternative to precious metals for large-scale conversion of biomass. However, it usually suffers from unsatisfactory activity. In this work, a nitrogen-doped carbon-alumina hybrid supported iron (Fe-N-C@Al2O3) catalyst is established for chemoselective HDO of carboxylic acids to hydrocarbons. By using stearic acid HDO as the model reaction, n-octadecane and n-heptadecane are produced with yields of 91.9% and 6.0%, respectively. Triglycerides can also be converted into liquid alkanes with a total molar yield of >92%. In addition, the iron catalyst can chemoselectively catalyze the HDO of the carboxylic acid group in the presence of other functional groups such as an aromatic ring. This chemoselectivity has rarely been seen before because the aromatic ring is usually more easily hydrogenated in comparison to HDO of the carboxylic acid group. The characterization results showed that both the formation of a nitrogen-doped carbon-alumina hybrid and the iron loading are important for the Lewis basicity of these catalysts, in order to adsorb the acid substrates. The addition of melamine as the nitrogen precursor during pyrolysis eliminates undesired reactions between the iron precursor and alumina support to form an inactive hercynite phase, leading to the formation of an Fe3C active phase for the hydrogenation of -COOH to -CH2OH and the hybrid of N-C and alumina for the HDO of -CH2OH to -CH3.
Li, Jiang,Zhang, Junjie,Wang, Shuai,Xu, Guangyue,Wang, Hao,Vlachos, Dionisios G.
p. 1564 - 1577
(2019/02/03)

Transition-State Interactions in a Promiscuous Enzyme: Sulfate and Phosphate Monoester Hydrolysis by Pseudomonas aeruginosa Arylsulfatase
Pseudomonas aeruginosa arylsulfatase (PAS) hydrolyzes sulfate and, promiscuously, phosphate monoesters. Enzyme-catalyzed sulfate transfer is crucial to a wide variety of biological processes, but detailed studies of the mechanistic contributions to its catalysis are lacking. We present linear free energy relationships (LFERs) and kinetic isotope effects (KIEs) of PAS and analyses of active site mutants that suggest a key role for leaving group (LG) stabilization. In LFERs PASWT has a much less negative Br?nsted coefficient (βleaving groupobs-Enz = 0.33) than the uncatalyzed reaction (βleaving groupobs = 1.81). This situation is diminished when cationic active site groups are exchanged for alanine. The considerable degree of bond breaking during the transition state (TS) is evidenced by an 18Obridge KIE of 1.0088. LFER and KIE data for several active site mutants point to leaving group stabilization by active site K375, in cooperation with H211. 15N KIEs and the increased sensitivity to leaving group ability of the sulfatase activity in neat D2O (βleaving groupH-D = +0.06) suggest that the mechanism for S-Obridge bond fission shifts, with decreasing leaving group ability, from charge compensation via Lewis acid interactions toward direct proton donation. 18Ononbridge KIEs indicate that the TS for PAS-catalyzed sulfate monoester hydrolysis has a significantly more associative character compared to the uncatalyzed reaction, while PAS-catalyzed phosphate monoester hydrolysis does not show this shift. This difference in enzyme-catalyzed TSs appears to be the major factor favoring specificity toward sulfate over phosphate esters by this promiscuous hydrolase, since other features are either too similar (uncatalyzed TS) or inherently favor phosphate (charge).
Van Loo, Bert,Berry, Ryan,Boonyuen, Usa,Mohamed, Mark F.,Golicnik, Marko,Hengge, AlVan C.,Hollfelder, Florian
p. 1363 - 1378
(2019/03/11)

Connecting Organometallic Ni(III) and Ni(IV): Reactions of Carbon-Centered Radicals with High-Valent Organonickel Complexes
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.
Bour, James R.,Ferguson, Devin M.,McClain, Edward J.,Kampf, Jeff W.,Sanford, Melanie S.
supporting information
p. 8914 - 8920
(2019/06/13)

One-pot fluorosulfurylation of Grignard reagents using sulfuryl fluoride
Herein, we report a new method for the one-pot syntheses of sulfonyl fluorides. Addition of an alkyl, aryl, or heteroaryl Grignard to a solution of sulfuryl fluoride at ambient temperature affords the desired sulfonyl fluorides in 18-78% yield. Furthermore, this method is applicable for in situ sequential reactions, whereby the Grignard reagent can be converted to the corresponding diarylsulfone, sulfonate ester, or sulfonamide in a one-pot process.
Lee, Cayo,Ball, Nicholas D.,Sammis, Glenn M.
supporting information
p. 14753 - 14756
(2019/12/23)

Palladium–Borane Cooperation: Evidence for an Anionic Pathway and Its Application to Catalytic Hydro-/Deutero-dechlorination
Metal–Lewis acid cooperation provides new opportunities in catalysis. In this work, we report a new type of palladium–borane cooperation involving anionic Pd0 species. The air-stable DPB palladium complex 1 (DPB=diphosphine-borane) was prepared and reacted with KH to give the Pd0 borohydride 2, the first monomeric anionic Pd0 species to be structurally characterized. The boron moiety acts as an acceptor towards Pd in 1 via Pd→B interaction, but as a donor in 2 thanks to B-H-Pd bridging. This enables the activation of C?Cl bonds and the system is amenable to catalysis, as demonstrated by the hydro-/deutero-dehalogenation of a variety of (hetero)aryl chlorides (20 examples, average yield 85 %).
Kameo, Hajime,Yamamoto, Jun,Asada, Ayaka,Nakazawa, Hiroshi,Matsuzaka, Hiroyuki,Bourissou, Didier
supporting information
p. 18783 - 18787
(2019/11/19)

Formation of hierarchically-ordered nanoporous silver foam and its electrocatalytic properties in reductive dehalogenation of organic compounds
Nanoporous silver foam on a glassy carbon electrode (AgNF/GC) was formed by cathodic deposition of silver from an acidic solution of AgBF4 at high current density. The material can be described (based on results of optical microscopy, SEM, TEM and XRD investigation) as hierarchically (micro/nano) porous matter with ca. 40 nm silver crystals assembled in irregular ca. 70-300 nm thick filaments arranged in a foam-like structure with ca. 20 μm cavities and ca. 7 μm walls. The AgNF surface area was estimated by pseudocapacitance measurement as ca. 12 times higher than the geometrical area. Reduction of bromobenzene and other aryl bromides containing redox-inactive (F-, CH3-, CH3O-) or redox-active (-NO2,-CN and CH3CO-) substituents, as well as alkyl bromides (CF3CHClBr, CF2Br2) on AgNF/GC was studied. The peak potentials of the processes assigned to debromination of the organic halides were less negative (up to +345 mV) than on smooth silver, indicating superior electrocatalytic properties of the nanoporous silver foam. Comparison of the CV peak currents of the processes on AgNF/GC and smooth silver, as well as their changes in cycling in different regimes allowed formation of a few kinds of electrocatalytically active sites on the AgNF surface to be suggested. Electrolysis of 1-bromo-4-fluorobenzene on the AgNF electrode led to fluorobenzene, and less than 1 mg of AgNF revealed performance comparable to 500 mg of smooth silver wire. The results can be utilized for creation of electrochemical sensors as well as for preparative detoxification of halogen-containing persistent organic pollutants.
Mishura, Andrey M.,Lytvynenko, Anton S.,Gavrilenko, Konstantin S.,Baranchikov, Alexander E.,Grabovaya, Natalia V.,Kiskin, Mikhail A.,Kolotilov, Sergey V.
p. 17499 - 17512
(2018/11/01)

Decarbonylation of Aromatic Aldehydes and Dehalogenation of Aryl Halides Using Maghemite-Supported Palladium Catalyst
A facile decarbonylation reaction of a variety of aromatic and heteroaromatic aldehydes using maghemite-supported palladium catalyst has been developed. The magnetic properties of catalyst facilitated an easy and efficient recovery of the catalyst from the reaction mixture using an external magnet. It was found that the catalyst could be reused up to four consecutive catalytic runs without a significant change in activity. In addition, the catalyst was also very effective in the dehalogenation of aryl halides. This is the first report on efficient utilization of directly immobilized Pd on maghemite in decarbonylation and dehalogenation reactions.
Ajda?i?, Vladimir,Nikoli?, Andrea,Simi?, Stefan,Manojlovi?, Dragan,Stojanovi?, Zoran,Nikodinovic-Runic, Jasmina,Opsenica, Igor M.
p. 119 - 126
(2017/12/27)

Highly efficient Sandmeyer reaction on immobilized CuI/CuII-based catalysts
Highly effective embodiment of Sandmeyer reaction has been revealed for Cu-based catalysts incorporating ionic liquid on Silochrom support. The most active catalyst (TOF = = 4000–8000 h–1) contains comparable amounts of cuprous and cupric chloride anions. The reported method allows one to carry out the reaction for anilines in the one-pot mode.
Tarkhanova, Irina G.,Gantman, Michail G.,Sigeev, Alexander S.,Maslakov, Konstantin I.,Zelikman, Vladimir M.,Beletskaya, Irina P.
p. 261 - 263
(2018/06/01)

A Predictive Model for the Decarboxylation of Silver Benzoate Complexes Relevant to Decarboxylative Coupling Reactions
Decarboxylative coupling reactions offer an attractive route to generate functionalized arenes from simple and readily available carboxylic acid coupling partners, yet they are underutilized due to limitations in the scope of carboxylic acid coupling partner. Here we report that the field effect parameter (F) has a substantial influence on the rate of decarboxylation of well-defined silver benzoate complexes. This finding provides the opportunity to surpass current substrate limitations associated with decarboxylation and to enable widespread utilization of decarboxylative coupling reactions.
Crovak, Robert A.,Hoover, Jessica M.
p. 2434 - 2437
(2018/02/28)

Palladium-mediated radical homocoupling reactions: A surface catalytic insight
In this contribution, we report a palladium nanoparticle-promoted reductive homocoupling of haloarenes that proceeds efficiently to produce corresponding bis-aryls in moderate to excellent yields using relatively low catalyst loading (1 mol%), and exhibits broad functional group tolerance. This work sheds light on how the surface state of Pd(0) nanoparticles plays a crucial role in the reactivity of catalytic systems. Notably, the appropriate choice of palladium salts for the preparation of the preformed nanocatalysts was a key parameter having a major impact on the catalytic activity; thus, the effect of halide anions on the reactivity of the as-prepared palladium nanoparticles could be assessed, with iodide anions being capable of inhibiting the corresponding homocoupling reaction. The homocoupling reaction mechanism has been further studied by means of radical trap and electron paramagnetic resonance (EPR) experiments, revealing that the reaction proceeds via radical intermediates. Taking into account these data, a plausible reaction mechanism based on single-electron transfer processes on the palladium nanoparticle surface is discussed.
Favier, Isabelle,Toro, Marie-Lou,Lecante, Pierre,Pla, Daniel,Gómez, Montserrat
p. 4766 - 4773
(2018/09/29)

Hypervalent Iodine(III)-Catalyzed Balz–Schiemann Fluorination under Mild Conditions
An unprecedented hypervalent iodine(III) catalyzed Balz–Schiemann reaction is described. In the presence of a hypervalent iodine compound, the fluorination reaction proceeds under mild conditions (25–60 °C), and features a wide substrate scope and good functional-group compatibility.
Xing, Bo,Ni, Chuanfa,Hu, Jinbo
p. 9896 - 9900
(2018/07/31)

Expanding the Balz–Schiemann Reaction: Organotrifluoroborates Serve as Competent Sources of Fluoride Ion for Fluoro-Dediazoniation
The Balz–Schiemann reaction endures as a method for the preparation of (hetero)aryl fluorides yet is eschewed due to the need for harsh conditions or high temperatures along with the need to isolate potentially explosive diazonium salts. In a departure from these conditions, we show that various organotrifluoroborates (RBF3?s) may serve as fluoride ion sources for solution-phase fluoro-dediazoniation in organic solvents under mild conditions. This methodology was successfully extended to a one-pot process obviating aryl diazonium salt isolation. Sterically hindered (hetero)anilines are fluorinated under unprecedentedly mild conditions in good-to-excellent yields. Taken together, this work expands the repertoire of RBF3?s to act as fluorine ion sources in an update to the classic Balz–Schiemann reaction.
Mohy El Dine, Tharwat,Sadek, Omar,Gras, Emmanuel,Perrin, David M.
supporting information
p. 14933 - 14937
(2018/09/25)

Application of trivalent iodine compounds as catalysts in Bal-Schiemann reaction
The invention discloses an application of trivalent iodine compounds shown in formula I and/or II in the description and used as catalysts in Bal-Schiemann reaction. The trivalent iodine compounds areused as the catalysts in the Bal-Schiemann reaction, so that the Bal-Schiemann reaction can be conducted at room temperature or near room temperature when a thermochemical method is used, and the reaction has mild reaction conditions, wide substrate use range and short reaction time, and is safe and easy to operate, products are easy to separate, and raw materials are simple and low in toxicity.
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Paragraph 0152; 0158

(2018/10/19)

Pd-PEPPSI complexes based on 1,2,4-triazol-3-ylidene ligands as efficient catalysts in the Suzuki—Miyaura reaction
The palladium complexes of the Pd-PEPPSI type with N-heterocyclic carbenes of the 1,2,4-triazole series were synthesized in 76—99% yields by the reactions of PdCl2 with 1,4-di- alkyl-1,2,4-triazolium salts in pyridine in the presence of KBr or KI as sources of halide ions and tetrabutylammonium salts as phase-transfer catalysts. The obtained complexes can be used as efficient catalysts for the Suzuki—Miyaura cross-coupling and are not inferior to the commercially available Pd-PEPPSI catalysts in activity.
Chernenko, A. Yu.,Astakhov,Pasyukov,Dorovatovskii,Zubavichus, Ya. V.,Khrustalev,Chernyshev
p. 79 - 84
(2018/04/27)

Palladium-metalated porous organic polymers as recyclable catalysts for chemoselective decarbonylation of aldehydes
A novel palladium nanoparticle (NP)-metalated porous organic ligand (Pd NPs/POL-xantphos) has been prepared for the chemoselective decarbonylation of aldehydes. This heterogenous catalyst not only has excellent catalytic activity and chemoselectivity, but also holds high activity after 10 runs of reuse. The effective usage of this method is demonstrated through the synthesis of biofuels such as furfuryl alcohol (FFA) via the highly chemoselective decarbonylation of biomass-derived 5-hydroxy-methylfurfural (HMF) with a TON up to 1540. More importantly, 9-fluorenone could be obtained in one step through the decarbonylation of 2-bromobenzaldehyde by using this heterogeneous catalyst.
Li, Wen-Hao,Li, Cun-Yao,Li, Yan,Tang, Hai-Tao,Wang, Heng-Shan,Pan, Ying-Ming,Ding, Yun-Jie
supporting information
p. 8446 - 8449
(2018/08/28)

Reactions of Arylsulfonate Electrophiles with NMe4F: Mechanistic Insight, Reactivity, and Scope
This paper describes a detailed study of the deoxyfluorination of aryl fluorosulfonates with tetramethylammonium fluoride (NMe4F) and ultimately identifies other sulfonate electrophiles that participate in this transformation. 19F NMR spectroscopic monitoring of the deoxyfluorination of aryl fluorosulfonates revealed the rapid formation of diaryl sulfates under the reaction conditions. These intermediates can proceed to fluorinated products; however, diaryl sulfate derivatives bearing electron-donating substituents react very slowly with NMe4F. Based on these findings, aryl triflate and aryl nonaflate derivatives were explored, since these cannot react to form diaryl sulfates. Aryl triflates were found to be particularly effective electrophiles for deoxyfluorination with NMe4F, and certain derivatives (i.e., those bearing electron-neutral/donating substituents) afforded higher yields than their aryl fluorosulfonate counterparts. Computational studies implicate a similar mechanism for deoxyfluorination of all the sulfonate electrophiles.
Schimler, Sydonie D.,Froese, Robert D. J.,Bland, Douglas C.,Sanford, Melanie S.
p. 11178 - 11190
(2018/09/12)

An Additive-Free, Base-Catalyzed Protodesilylation of Organosilanes
We report an additive-free, base-catalyzed C-, N-, O-, and S-Si bond cleavage of various organosilanes in mild conditions. The novel catalyst system exhibits high efficiency and good functional group compatibility, providing the corresponding products in good to excellent yields with low catalyst loadings. Overall, this transition-metal-free process may offer a convenient and general alternative to current employing excess bases, strong acids, or metal-catalyzed systems for the protodesilylation of organosilanes.
Yao, Wubing,Li, Rongrong,Jiang, Huajiang,Han, Deman
p. 2250 - 2255
(2018/02/23)

Mechanistic Study on Aryl-Exchange Reaction of Diaryl-λ3-iodane with Aryl Iodide
Because of its hyper-leaving ability, as well as its strong oxidizing ability, diaryl(triflato)-λ3-iodane transfers one of the aryl groups to iodoarenes simply upon gentle heating (>85 °C) in nonpolar solvents. We have performed an in-depth mechanistic study of this unusual aryl transfer reaction. A combination of experimental (product analysis, kinetic study, and substituent effects) and density functional theoretical approaches revealed that the reaction proceeds through a concerted bimolecular transition state, in which ipso-carbon binds loosely to both iodine centers. We also evaluated electronic effects on the thermodynamic stability of diaryl-λ3-iodanes.
Masumoto, Yui,Miyamoto, Kazunori,Iuchi, Takuto,Ochiai, Masahito,Hirano, Keiichi,Saito, Tatsuo,Wang, Chao,Uchiyama, Masanobu
p. 289 - 295
(2018/02/19)

Nickel-catalyzed C-O bond reduction of aryl and benzyl 2-pyridyl ethers
The reduction of aryl and benzyl 2-pyridyl ethers with sodium isopropoxide was carried out via nickel-catalyzed C-OPy bond cleavage, giving reductive products in reasonable to excellent yields. This method allowed the 2-pyridyloxy group to be directly rem
Li, Jing,Wang, Zhong-Xia
supporting information
p. 2138 - 2141
(2018/03/06)