- Mechanistic insight on the hydrogenation of conjugated alkenes with H 2 catalyzed by early main-group metal catalysts
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Density functional theory calculations have been performed to investigate the molecular mechanism of the hydrogenation reactions of 1,1-diphenylethylene and myrcene catalyzed by the actual calcium hydride catalyst, CaH(dipp-nacnac)(thf) (dipp-nacnac = CH{
- Zeng, Guixiang,Li, Shuhua
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Read Online
- THE STOICHIOMETRIC HYDROGENATION OF SUBSTITUTED PHENYL ALKENES BY HYDRIDOCOBALT TETRACARBONYL
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The relative rates of hydrogenation of a series of styrenes, phenylpropenes, 1,1-diphenylethylenes, and 1,1-diphenylpropenes were measured.Compared to 1,1-diphenylethylene (k2=2.42*10-2 l mol-1 sec-1), 1,1-diphe
- Roth, Jerome A.,Wiseman, Paul
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Read Online
- Complexes between lithium cation and diphenylalkanes in the gas phase: The pincer effect
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The gas-phase lithium cation basicities (LCB values, Gibbs free energies of binding) of α,ω)-diphenylal-kanes Ph-(CH2) n-Ph (n = 2, 3, or 7) and 1,1-diphenylethane Ph-CH(Me)-Ph were investigated by means of Fourier-transform ion cyclotron resonance (FTICR) mass spectrometry. Their structures, and those of the corresponding Li+ complexes were optimized at the B3LYP/6-31G(d) level and their relative stabilities calculated at the B3LYP/6-311+G(3df,2p)//B3LYP/6-31G(d) level. Whereas the most stable conformers of the free diphenylalkanes were found to adopt a completely stretched aliphatic chain connecting the two benzene rings, the most stable Li+ complexes correspond to conformers in which the alkali metal cation interacts simultaneously with both benzene rings through the folding of the aliphatic chain ("pincer effect"). This chelation brings about a significant enhancement of the Li+ binding enthalpies (LBE values), which were calculated to be approximately 75 kJ mor-1 higher than those evaluated for conventional (singly coordinated) π complexes in which the metal cation interacts with only one of the benzene rings. The increase of the corresponding lithium cation basicities, however, (Gibbs free energies of Li+ binding, LCB values) was calculated to be smaller by approximately 15 kJ mol-1 as the pincer effect is entropically disfavored. The good agreement between the calculated LCB values, assuming a statistical distribution of the different conformers present in the gas phase, and the experimental LCB values measured by means of FTICR mass spectrometry are considered indirect evidence of the existence of the pincer effect.
- Gal, Jean-Francois,Maria, Pierre-Charles,Mo, Otilia,Yanez, Manuel,Kuck, Dietmar
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Read Online
- Ga+-catalyzed hydrosilylation? about the surprising system Ga+/HSiR3/olefin, proof of oxidation with subvalent Ga+and silylium catalysis with perfluoroalkoxyaluminate anions
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Already 1 mol% of subvalent [Ga(PhF)2]+[pf]- ([pf]- = [Al(ORF)4]-, RF = C(CF3)3) initiates the hydrosilylation of olefinic double bonds under mild conditions. Reactions with HSiMe3 and HSiEt3 as substrates efficiently yield anti-Markovnikov and anti-addit
- Barthélemy, Antoine,Glootz, Kim,Hanske, Annaleah,Krossing, Ingo,Scherer, Harald
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p. 439 - 453
(2022/01/22)
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- H2 Evolution Upon Hydrolysis of Ammonia-Borane Catalyzed by Porphyrin Stabilized Nanocatalysts
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Abstract: Ammonia-borane (AB) is one of the most promising fuel forms for the hydrogen economy, but the reaction requires a good catalyst to accelerate this hydrolysis reaction under ambient conditions. Here, H2 evolution upon hydrolysis of amm
- Zhang, Nuonuo,Liu, Genjiang,Sun, Yao,Wang, Yanlan,Yan, Jiaying,Liu, Xiang
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p. 2272 - 2278
(2021/01/04)
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- Hydrolysis of B2pin2 over Pd/C Catalyst: High Efficiency, Mechanism, and in situ Tandem Reaction
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A facile and effective synthesis of H2 or D2 from Pd/C catalyzed hydrolysis of B2pin2 has first been developed. Among them, B2pin2 is frequently used for borylation reaction, and has rarely been used for hydrogen evolution. The kinetic isotope effects (KIEs) and tandem reaction for diphenylacetylene and norbornene hydrogenation have confirmed both two H atoms of H2 gas are provided from H2O. This is contrary to other boron compounds hydrolysis (including NH3BH3, NaBH4), which generates H2 with only one H atom provided by water and the other one by boron compounds. Note that the hydrolysis of B2pin2 in D2O also provides an easy and useful synthesis of D2.
- Li, Ning,Shen, Jialu,Liu, Xiang
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supporting information
p. 2797 - 2800
(2021/02/16)
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- Sustainable System for Hydrogenation Exploiting Energy Derived from Solar Light
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Herein described is a sustainable system for hydrogenation that uses solar light as the ultimate source of energy. The system consists of two steps. Solar energy is captured and chemically stored in the first step; exposure of a solution of azaxanthone in ethanol to solar light causes an energy storing dimerization of the ketone to produce a sterically strained 1,2-diol. In the second step, the chemical energy stored in the vicinal diol is released and used for hydrogenation; the diol offers hydrogen onto alkenes and splits back to azaxanthone, which is easily recovered and reused repeatedly for capturing solar energy.
- Ishida, Naoki,Kamae, Yoshiki,Ishizu, Keigo,Kamino, Yuka,Naruse, Hiroshi,Murakami, Masahiro
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supporting information
p. 2217 - 2220
(2021/02/16)
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- Acid- and Base-Catalyzed Hydrolytic Hydrogen Evolution from Diboronic Acid
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The efficient production of H2 from hydrogen-rich sources, particularly from water, is a crucial task and a great challenge, both as a sustainable energy source and on the laboratory scale for hydrogenation reactions. Herein, a facile and effective synthesis of H2 and D2 from only acid- or base-catalyzed metal-free hydrolysis of B2(OH)4, a current borylation reagent, has been developed without any transition metal or ligand. Acid-catalyzed H2 evolution was completed in 4 min, whereas the base-catalyzed process needed 6 min. The large kinetic isotopic effects for this reaction with D2O, deuteration experiments and mechanistic studies have confirmed that both H atoms of H2 originate from water using either of these reactions. This new, metal-free catalytic system holds several advantages, such as high efficiency, simplicity of operation, sustainability, economy, and potential further use.
- Wang, Yi,Shen, Jialu,Huang, Yu,Liu, Xiang,Zhao, Qiuxia,Astruc, Didier
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supporting information
p. 3013 - 3018
(2021/03/26)
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- Indium Tribromide-Catalysed Transfer-Hydrogenation: Expanding the Scope of the Hydrogenation and of the Regiodivergent DH or HD Addition to Alkenes
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The transfer-hydrogenation as well as the regioselective and regiodivergent addition of H?D from regiospecific deuterated dihydroaromatic compounds to a variety of 1,1-di- and trisubstituted alkenes was realised with InBr3 in dichloro(m)ethane. In comparison with the previously reported BF3?Et2O-catalysed process, electron-deficient aryl-substituents can be applied reliably and thereby several restrictions could be lifted, and new types of substrates could be transformed successfully in hydrodeuterogenation as well as deuterohydrogenation transfer-hydrogenation reactions.
- Li, Luomo,Hilt, Gerhard
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supporting information
p. 11221 - 11225
(2021/06/25)
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- Boosting homogeneous chemoselective hydrogenation of olefins mediated by a bis(silylenyl)terphenyl-nickel(0) pre-catalyst
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The isolable chelating bis(N-heterocyclic silylenyl)-substituted terphenyl ligand [SiII(Terp)SiII] as well as its bis(phosphine) analogue [PIII(Terp)PIII] have been synthesised and fully characterised. Their reaction with Ni(cod)2(cod = cycloocta-1,5-diene) affords the corresponding 16 VE nickel(0) complexes with an intramolecularη2-arene coordination of Ni, [E(Terp)E]Ni(η2-arene) (E = PIII, SiII; arene = phenylene spacer). Due to a strong cooperativity of the Si and Ni sites in H2activation and H atom transfer, [SiII(Terp)SiII]Ni(η2-arene) mediates very effectively and chemoselectively the homogeneously catalysed hydrogenation of olefins bearing functional groups at 1 bar H2pressure and room temperature; in contrast, the bis(phosphine) analogous complex shows only poor activity. Catalytic and stoichiometric experiments revealed the important role of the η2-coordination of the Ni(0) site by the intramolecular phenylene with respect to the hydrogenation activity of [SiII(Terp)SiII]Ni(η2-arene). The mechanism has been established by kinetic measurements, including kinetic isotope effect (KIE) and Hammet-plot correlation. With this system, the currently highest performance of a homogeneous nickel-based hydrogenation catalyst of olefins (TON = 9800, TOF = 6800 h?1) could be realised.
- Lücke, Marcel-Philip,Yao, Shenglai,Driess, Matthias
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p. 2909 - 2915
(2021/03/14)
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- Synthesis of Deuterated (E)-Alkene through Xanthate-Mediated Hydrogen-Deuterium Exchange Reactions
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Herein we have developed a reversible hydrogen-deuterium exchange reaction of nonactivated olefins. By using EtOCS2K as a mediator, the H/D exchange reaction was realized through repeated addition and elimination reactions, demonstrating reversible H/D exchange between ordinary olefins and deuterated olefins. Using the lowest cost D2O without precious metal catalysts and ligands, a broad spectrum of compatibility of functional groups was achieved.
- Li, Jiaming,Li, Jian,Ji, Xiaoliang,He, Runfa,Liu, Yang,Chen, Zebin,Huang, Yubing,Liu, Qiang,Li, Yibiao
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supporting information
p. 7412 - 7417
(2021/10/01)
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- Ligand-enabled and magnesium-activated hydrogenation with earth-abundant cobalt catalysts
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Replacing expensive noble metals like Pt, Pd, Ir, Ru, and Rh with inexpensive earth-abundant metals like cobalt (Co) is attracting wider research interest in catalysis. Cobalt catalysts are now undergoing a renaissance in hydrogenation reactions. Herein, we describe a hydrogenation method for polycyclic aromatic hydrocarbons (PAHs) and olefins with a magnesium-activated earth-abundant Co catalyst. When diketimine was used as a ligand, simple and inexpensive metal salts of CoBr2in combination with magnesium showed high catalytic activity in the site-selective hydrogenation of challenging PAHs under mild conditions. Co-catalyzed hydrogenation enabled the reduction of two side aromatics of PAHs. A wide range of PAHs can be hydrogenated in a site-selective manner, which provides a cost-effective, clean, and selective strategy to prepare partially reduced polycyclic hydrocarbon motifs that are otherwise difficult to prepare by common methods. The use of well-defined diketimine-ligated Co complexes as precatalysts for selective hydrogenation of PAHs and olefins is also demonstrated.
- Han, Bo,Jiao, Hongmei,Ma, Haojie,Wang, Jijiang,Zhang, Miaomiao,Zhang, Yuqi
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p. 39934 - 39939
(2021/12/31)
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- Reductive activation and hydrofunctionalization of olefins by multiphoton tandem photoredox catalysis
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The conversion of olefin feedstocks to architecturally complex alkanes represents an important strategy in the expedient generation of valuable molecules for the chemical and life sciences. Synthetic approaches are reliant on the electrophilic activation of unactivated olefins, necessitating functionalization with nucleophiles. However, the reductive functionalization of unactivated and less activated olefins with electrophiles remains an ongoing challenge in synthetic chemistry. Here, we report the nucleophilic activation of inert styrenes through a photoinduced direct single electron reduction to the corresponding nucleophilic radical anion. Central to this approach is the multiphoton tandem photoredox cycle of the iridium photocatalyst [Ir(ppy)2(dtbbpy)] PF6, which triggers in situ formation of a high-energy photoreductant that selectively reduces styrene olefinic π bonds to radical anions without stoichiometric reductants or dissolving metals. This mild strategy enables the chemoselective reduction and hydrofunctionalization of styrenes to furnish valuable alkane and tertiary alcohol derivatives. Mechanistic studies support the formation of a styrene olefinic radical anion intermediate and a Birch-type reduction involving two sequential single electron transfers. Overall, this complementary mode of olefin activation achieves the hydrofunctionalization of less activated alkenes with electrophiles, adding value to abundant olefins as valuable building blocks in modern synthetic protocols.
- Czyz, Milena L.,Taylor, Mitchell S.,Horngren, Tyra H.,Polyzos, Anastasios
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p. 5472 - 5480
(2021/06/01)
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- A facile and versatile electro-reductive system for hydrodefunctionalization under ambient conditions
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A general electrochemical system for reductive hydrodefunctionalization is described, employing the inexpensive and easily available triethylamine (Et3N) as a sacrificial reductant. This protocol is characterized by facile operation, sustainable conditions, and exceptionally wide substrate scope covering the cleavage of C-halogen, N-S, N-C, O-S, O-C, C-C and C-N bonds. Notably, the selectivity and capability of reduction can be conveniently switched by simple incorporation or removal of an alcohol as a co-solvent.
- Huang, Binbin,Guo, Lin,Xia, Wujiong
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p. 2095 - 2103
(2021/03/26)
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- Metal-Free Heterogeneous Semiconductor for Visible-Light Photocatalytic Decarboxylation of Carboxylic Acids
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A suitable protocol for the photocatalytic decarboxylation of carboxylic acids was developed with metal-free ceramic boron carbon nitrides (BCN). With visible light irradiation, BCN oxidize carboxylic acids to give carbon-centered radicals, which were trapped by hydrogen atom donors or employed in the construction of the carbon-carbon bond. In this system, both (hetero)aromatic and aliphatic acids proceed the decarboxylation smoothly, and C-H, C-D, and C-C bonds are formed in moderate to high yields (35 examples, yield up to 93%). Control experiments support a radical process, and isotopic experiments show that methanol is employed as the hydrogen atom donor. Recycle tests and gram-scale reaction elucidate the practicability of the heterogeneous ceramic BCN photoredox system. It provides an alternative to homogeneous catalysts in the valuable carbon radical intermediates formation. Moreover, the metal-free system is also applicable to late-stage functionalization of anti-inflammatory drugs, such as naproxen and ibuprofen, which enrich the chemical toolbox.
- Shi, Jiale,Yuan, Tao,Zheng, Meifang,Wang, Xinchen
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p. 3040 - 3047
(2021/03/09)
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- Preliminary investigations on the catalytic hydrogenation of polycyclic aromatic hydrocarbons via WGSR
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The water-gas shift reaction (WGSR) is a crucial reaction in the direct liquefaction of lignite in a syngas (CO + H2) system. In this study, anthracene was utilized as a polycyclic model compound of lignite, to which hydrogen is donated by the H2/D2 produced from CO and H2O/D2O via the WGSR. The results show that the model compound of the polycyclic aromatic hydrocarbon in coal (anthracene) undergoes partial cracking and polycondensation under non-hydrogen-donor conditions at 400 °C. In addition, WGSR catalyzed by NiO can generate hydrogen for the hydrogenation of anthracene. Comparing the mass spectra of deuterated products with those of conventional hydrogenation products by isotope labeling, the alkyl side chain positions of toluene, 1,4-xylene, methylnaphthalene, 1,1-diphenylethylene, methylanthracene and other compounds are prone to deuteration, enabling speculation of the main hydrogenation route of anthracene, which provides theoretical support for the catalytic hydrogenation in direct liquefaction of lignite in a syngas (CO + H2) system.
- Chen, Dabo,Gu, Jiale,Huang, Sheng,Li, Huan,Wu, Shiyong,Wu, Youqing
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- Rhodium-Catalyzed meta-Selective C?H Carboxylation Reaction of 1,1-Diarylethylenes via Hydrorhodation-Rhodium Migration
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A meta-selective C?H carboxylation reaction of 1,1-diarylethylene derivatives with CO2 by using a rhodium catalyst with NaOiPr as a stoichiometric reductant has been achieved. Together with hydrogenation of the ethylene moiety, a carboxyl group was introduced to the meta-position of the aryl ring with high selectivity over the ortho-positions. Experimental and computational mechanistic studies indicate that this carboxylation reaction proceeds via hydrorhodation on the ethylene moiety, followed by 1,4-rhodium migration and successive 1,2-rhodium migration on the aryl ring. The use of a bulky phosphine ligand seems to be the key to this unusual aryl-to-aryl 1,2-rhodium shift.
- Caner, Joaquim,Iwasawa, Nobuharu,Saito, Takanobu,Toriumi, Naoyuki
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supporting information
p. 23349 - 23356
(2021/09/18)
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- HIGHLY SELECTIVE ELECTROCHEMICAL HYDROGENATION OF ALKYNES
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Disclosed are electrochemical methods to prepare an alkane or an alkene, such as a cis- alkene, from an alkyne, or an alkane from an alkene. The method utilizes an electrochemical cell having a cathode and an anode and a reactor.
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Page/Page column 7
(2020/10/20)
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- Bisoxazoline-pincer ligated cobalt-catalyzed hydrogenation of alkenes
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The efficient and atom economical hydrogenation of alkenes using a novel bisoxazoline ligated cobalt complex has been developed. The hydrogenation of a variety of alkenes containing electron neutral and electron-donating groups proceeds in high yield, whi
- Ritz, Mikhaila D.,Parsons, Astrid M.,Palermo, Philip N.,Jones, William D.
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supporting information
(2020/02/13)
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- Organoborohydride-catalyzed Chichibabin-type C4-position alkylation of pyridines with alkenes assisted by organoboranes
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The first NaBEt3H-catalyzed intermolecular Chichibabin-type alkylation of pyridine and its derivatives with alkenes as the latent nucleophiles is presented with the assistance of BEt3, and a series of branched C4-alkylation pyridines, even highly congested all-carbon quaternary center-containing triarylmethanes can be obtained in a regiospecific manner. Therefore, the conventional reliance on high cost and low availability transition metal catalysts, prior formation of N-activated pyridines, organometallic reagents, and extra oxidation operation for the construction of a C-C bond at the C4-position of the pyridines in previous methods are not required. The corresponding mechanism and the key roles of the organoborane were elaborated by the combination of H/D scrambling experiments, 11B NMR studies, intermediate trapping experiments and computational studies. This straightforward and mechanistically distinct organocatalytic technology not only opens a new door for the classical but still far less well-developed Chichibabin-type reaction, but also sets up a new platform for the development of novel C-C bond-forming methods.
- Guan, Wei,Li, Runhan,Li, Xiaohong,Li, Yanfei,Wang, Ying,Xiong, Tao,Yin, Jianjun,Zhang, Ge,Zhang, Qian
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p. 11554 - 11561
(2020/11/23)
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- Diboron-Mediated Rhodium-Catalysed Transfer Hydrogenation of Alkenes and Carbonyls
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A diboron-mediated rhodium-catalysed transfer hydrogenation system using water as the hydrogen donor is developed. In addition to a series of alkenes with good functional group tolerance, this rhodium-based catalytic system also effectively reduces aldehydes and ketones. A plausible mechanism involving the RhI-catalysed hydrogen generation and Rh0-catalysed hydrogenation is proposed for the reaction.
- Lin, Xiao,Wang, Yuhan,Hu, Yan,Zhu, Wanjiang,Dou, Xiaowei
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supporting information
p. 1046 - 1049
(2020/02/25)
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- Hydrogenation reaction method
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The invention relates to a hydrogenation reaction method, and belongs to the technical field of organic synthesis. The hydrogenation reaction method provided by the invention comprises the following steps: carrying out a hydrogen transfer reaction on a hydrogen acceptor compound, pinacol borane and a catalyst in a solvent in the presence of proton hydrogen, so that the hydrogen acceptor compound is subjected to a hydrogenation reaction; the catalyst is one or more than two of a palladium catalyst, an iridium catalyst and a rhodium catalyst; the hydrogen acceptor compound comprises one or morethan two functional groups of carbon-carbon double bonds, carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogentriple bonds and epoxy. The method is mild in reaction condition, easy to operate, high in yield, short in reaction time, wide in substrate application range, suitable for carbon-carbon double bonds,carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogen triple bonds and epoxy functional groups, good in selectivity and high in reaction specificity.
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Paragraph 0034; 0137-0140
(2020/05/14)
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- Generalized Chemoselective Transfer Hydrogenation/Hydrodeuteration
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A generalized, simple and efficient transfer hydrogenation of unsaturated bonds has been developed using HBPin and various proton reagents as hydrogen sources. The substrates, including alkenes, alkynes, aromatic heterocycles, aldehydes, ketones, imines, azo, nitro, epoxy and nitrile compounds, are all applied to this catalytic system. Various groups, which cannot survive under the Pd/C/H2 combination, are tolerated. The activity of the reactants was studied and the trends are as follows: styrene'diphenylmethanimine'benzaldehyde'azobenzene'nitrobenzene'quinoline'acetophenone'benzonitrile. Substrates bearing two or more different unsaturated bonds were also investigated and transfer hydrogenation occurred with excellent chemoselectivity. Nano-palladium catalyst in situ generated from Pd(OAc)2 and HBPin extremely improved the TH efficiency. Furthermore, chemoselective anti-Markovnikov hydrodeuteration of terminal aromatic olefins was achieved using D2O and HBPin via in situ HD generation and discrimination. (Figure presented.).
- Wang, Yong,Cao, Xinyi,Zhao, Leyao,Pi, Chao,Ji, Jingfei,Cui, Xiuling,Wu, Yangjie
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supporting information
p. 4119 - 4129
(2020/08/10)
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- Regiodivergent DH or HD Addition to Alkenes: Deuterohydrogenation versus Hydrodeuterogenation
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The regioselective and regiodivergent addition of H-D to a variety of 1,1-diarylalkenes was realized utilizing selectively deuterated dihydroaromatic compounds, which were generated by cobalt catalysis. The reaction was initiated by catalytic amounts of B
- Hilt, Gerhard,Li, Luomo
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supporting information
(2020/03/03)
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- Nitrenium Salts in Lewis Acid Catalysis
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Molecular compounds featuring nitrogen atoms are typically regarded as Lewis bases and are extensively employed as donor ligands in coordination chemistry or as nucleophiles in organic chemistry. By contrast, electrophilic nitrogen-containing compounds are much rarer. Nitrenium cations are a new family of nitrogen-based Lewis acids, the reactivity of which remains largely unexplored. In this work, nitrenium ions are explored as catalysts in five organic transformations. These reactions are the first examples of Lewis acid catalysis employing nitrogen as the site of substrate activation. Moreover, these compounds are readily accessed from commercially available reagents and exhibit remarkable stability toward moisture, allowing for benchtop transformations without the need to pretreat solvents.
- Mehta, Meera,Goicoechea, Jose M.
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supporting information
p. 2715 - 2719
(2020/01/24)
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- Exploring the Limits of π-Acid Catalysis Using Strongly Electrophilic Main Group Metal Complexes: The Case of Zinc and Aluminium
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The catalytic activity of cationic NHC-ZnII and NHC-AlIII (NHC=N-heterocyclic carbene) complexes in reactions that require the electrophilic activation of soft C?C π bonds has been studied. The former proved able to act as a soft π-L
- Tian, Jiaxin,Chen, Yan,Vayer, Marie,Djurovic, Alexandre,Guillot, Régis,Guermazi, Refka,Dagorne, Samuel,Bour, Christophe,Gandon, Vincent
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p. 12831 - 12838
(2020/09/16)
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- Bidentate NHC-Cobalt Catalysts for the Hydrogenation of Hindered Alkenes
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Herein, we report a series of easily accessible bidentate N-heterocyclic carbene (NHC) cobalt catalysts, which enable the hydrogenation of hindered alkenes under mild conditions. The four-coordinated bidentate NHC-Co(II) complexes were characterized by X-ray diffraction, elemental analysis, ESI-HRMS, and magnetic moment measurements, revealing a distorted-tetrahedral geometry and a high-spin configuration of the metal center. The activity of the in situ formed catalytic system, which was obtained from easily available NHC precursors, CoCl2, and NaHBEt3, was identical with those of well-defined NHC-cobalt catalysts. This highlights the potential utility of this reaction system.
- Wei, Zeyuan,Wang, Yujie,Li, Yibiao,Ferraccioli, Raffaella,Liu, Qiang
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p. 3082 - 3087
(2020/10/02)
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- Synthesis of [1]benzothiopheno[2,3-b][1]benzothiophene derivatives through iodine-mediated sulfuration reaction of 1,1-diarylethylenes
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Acceleration of the reaction for the synthesis of [1]benzothiopheno[2,3-b][1]benzothiophenes (BTBTs) from 1,1-diarylethylenes was accomplished by the addition of molecular iodine. Postulated intermediates 3-arylbenzo[b]thiophenes were also selectively prepared by simply changing the amount of iodine and the reaction time.
- Sakai, Shuta,Sato, Kazuki,Yoshida, Kazuhiro
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supporting information
(2019/12/27)
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- Chemoselective Homologation-Deoxygenation Strategy Enabling the Direct Conversion of Carbonyls into (n+1)-Halomethyl-Alkanes
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The sequential installation of a carbenoid and a hydride into a carbonyl, furnishing halomethyl alkyl derivatives, is reported. Despite the employment of carbenoids as nucleophiles in reactions with carbon-centered electrophiles, sp3-type alkyl halides remain elusive materials for selective one-carbon homologations. Our tactic levers on using carbonyls as starting materials and enables uniformly high yields and chemocontrol. The tactic is flexible and is not limited to carbenoids. Also, diverse carbanion-like species can act as nucleophiles, thus making it of general applicability.
- Citarella, Andrea,Holzer, Wolfgang,Ielo, Laura,Langer, Thierry,Miele, Margherita,Pace, Vittorio,Urban, Ernst,Zehl, Martin
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supporting information
p. 7629 - 7634
(2020/10/12)
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- "bulky-Yet-Flexible" α-Diimine Palladium-Catalyzed Reductive Heck Cross-Coupling: Highly Anti-Markovnikov-Selective Hydroarylation of Alkene in Air
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To pursue a highly regioselective and efficient reductive Heck reaction, a series of moisture-and air-stable α-diimine palladium precatalysts were rationally designed, readily synthesized, and fully characterized. The relationship between the structures of the palladium complexes and the catalytic properties was investigated. It was revealed that the"bulky-yet-flexible"palladium complexes allowed highly anti-Markovnikov-selective hydroarylation of alkenes with (hetero)aryl bromides under aerobic conditions. Further synthetic application of the present protocol could provide rapid and straightforward access to functional and biologically active molecules.
- Yang, Xu-Wen,Li, Dong-Hui,Song, A-Xiang,Liu, Feng-Shou
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p. 11750 - 11765
(2020/10/23)
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- Unexpected Nickel Complex Speciation Unlocks Alternative Pathways for the Reactions of Alkyl Halides with dppf-Nickel(0)
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The mechanism of the reactions between dppf-Ni0 complexes and alkyl halides has been investigated using kinetic and mechanistic experiments and DFT calculations. The active species is [Ni(κ2-dppf)(κ1-dppf)], which undergoes a halide abstraction reaction with alkyl halides and rapidly captures the alkyl radical that is formed. The rates of the reactions of [Ni(COD)(dppf)] with alkyl halides and the yields of prototypical nickel-catalyzed Kumada cross-coupling reactions of alkyl halides are shown to be significantly improved by the addition of free dppf ligand.
- Greaves, Megan E.,Lloyd-Jones, Guy C.,Maseras, Feliu,Nelson, David J.,Ronson, Thomas O.,Sproules, Stephen
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p. 10717 - 10725
(2020/11/09)
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- Cobaloxime Catalysis: selective synthesis of alkenylphosphine oxides under visible light
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Direct activation of H-phosphine oxide to react with an unsaturated carbon-carbon bond is a straightforward approach for accessing alkenylphosphine oxides, which shows significant applications in both synthetic and material fields. However, expensive metals and strong oxidants are typically required to realize the transformation. Here, we demonstrate the utility of earth-abundant cobaloxime to convert H-phosphine oxide into its reactive radical species under visible light irradiation. The radical species thus generated can be utilized to functionalize alkenes and alkynes without any external photosensitizer and oxidant. The coupling with terminal alkene generates E-alkenylphosphine oxide with excellent chemo- A nd stereoselectivity. The reaction with terminal alkyne yields linear E-alkenylphosphine oxide via neutral radical addition, while addition with internal ones generates cyclic benzophosphine oxides and hydrogen. Mechanistic studies on radical trapping experiments, electron spin resonance studies, and spectroscopic measurements confirm the formation of phosphinoyl radical and cobalt intermediates that are from capturing the electron and proton eliminated from H-phosphine oxide. The highlight of our mechanistic investigation is the dual role played by cobaloxime, viz., both as the visible light absorber to activate the P(O)-H bond as well as a hydrogen transfer agent to influence the reaction pathway. This synergetic feature of the cobaloxime catalyst preforming multiple functions under ambient condition provides a convergent synthetic approach to vinylphosphine oxides directly from H-phosphine oxides and alkenes (or alkynes).
- Liu, Wen-Qiang,Lei, Tao,Zhou, Shuai,Yang, Xiu-Long,Li, Jian,Chen, Bin,Sivaguru, Jayaraman,Tung, Chen-Ho,Wu, Li-Zhu
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p. 13941 - 13947
(2019/09/30)
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- Cobaloxime Catalysis: Selective Synthesis of Alkenylphosphine Oxides under Visible Light
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Direct activation of H-phosphine oxide to react with an unsaturated carbon-carbon bond is a straightforward approach for accessing alkenylphosphine oxides, which shows significant applications in both synthetic and material fields. However, expensive metals and strong oxidants are typically required to realize the transformation. Here, we demonstrate the utility of earth-abundant cobaloxime to convert H-phosphine oxide into its reactive radical species under visible light irradiation. The radical species thus generated can be utilized to functionalize alkenes and alkynes without any external photosensitizer and oxidant. The coupling with terminal alkene generates E-alkenylphosphine oxide with excellent chemo- and stereoselectivity. The reaction with terminal alkyne yields linear E-alkenylphosphine oxide via neutral radical addition, while addition with internal ones generates cyclic benzophosphine oxides and hydrogen. Mechanistic studies on radical trapping experiments, electron spin resonance studies, and spectroscopic measurements confirm the formation of phosphinoyl radical and cobalt intermediates that are from capturing the electron and proton eliminated from H-phosphine oxide. The highlight of our mechanistic investigation is the dual role played by cobaloxime, viz., both as the visible light absorber to activate the P(O)-H bond as well as a hydrogen transfer agent to influence the reaction pathway. This synergetic feature of the cobaloxime catalyst preforming multiple functions under ambient condition provides a convergent synthetic approach to vinylphosphine oxides directly from H-phosphine oxides and alkenes (or alkynes).
- Liu, Wen-Qiang,Lei, Tao,Zhou, Shuai,Yang, Xiu-Long,Li, Jian,Chen, Bin,Sivaguru, Jayaraman,Tung, Chen-Ho,Wu, Li-Zhu
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p. 13941 - 13947
(2019/09/30)
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- Alkene Transfer Hydrogenation with Alkaline-Earth Metal Catalysts
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The alkene transfer hydrogenation (TH) of a variety of alkenes has been achieved with simple AeN′′2 catalysts [Ae=Ca, Sr, Ba; N′′=N(SiMe3)2] using 1,4-cyclohexadiene (1,4-CHD) as a H source. Reaction of 1,4-CHD with AeN′′2 gave benzene, N′′H, and the metal hydride species N′′AeH (or aggregates thereof), which is a catalyst for alkene hydrogenation. BaN′′2 is by far the most active catalyst. Hydrogenation of activated C=C bonds (e.g. styrene) proceeded at room temperature without polymer formation. Unactivated (isolated) C=C bonds (e.g. 1-hexene) needed a higher temperature (120 °C) but proceeded without double-bond isomerization. The ligands fully control the course of the catalytic reaction, which can be: 1) alkene TH, 2) 1,4-CHD dehydrogenation, or 3) alkene polymerization. DFT calculations support formation of a metal hydride species by deprotonation of 1,4-CHD followed by H transfer. Convenient access to larger quantities of BaN′′2, its high activity and selectivity, and the many advantages of TH make this a simple but attractive procedure for alkene hydrogenation.
- Bauer, Heiko,Thum, Katharina,Alonso, Mercedes,Fischer, Christian,Harder, Sjoerd
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supporting information
p. 4248 - 4253
(2019/03/07)
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- Cobalt-Catalyzed Hydrogenations via Olefin Cobaltate and Hydride Intermediates
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Redox noninnocent ligands are a promising tool to moderate electron transfer processes within base-metal catalysts. This report introduces bis(imino)acenaphthene (BIAN) cobaltate complexes as hydrogenation catalysts. Sterically hindered trisubstituted alkenes, imines, and quinolines underwent clean hydrogenation under mild conditions (2-10 bar, 20-80 °C) by use of the stable catalyst precursor [(DippBIAN)CoBr2] and the cocatalyst LiEt3BH. Mechanistic studies support a homogeneous catalysis pathway involving alkene and hydrido cobaltates as active catalyst species. Furthermore, considerable reaction acceleration by alkali cations and Lewis acids was observed. The dinuclear hydridocobaltate anion with bridging hydride ligands was isolated and fully characterized.
- Sandl, Sebastian,Maier, Thomas M.,Van Leest, Nicolaas P.,Kr?ncke, Susanne,Chakraborty, Uttam,Demeshko, Serhiy,Koszinowski, Konrad,De Bruin, Bas,Meyer, Franc,Bodensteiner, Michael,Herrmann, Carmen,Wolf, Robert,Von Jacobi Wangelin, Axel
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p. 7596 - 7606
(2019/08/20)
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- Visible-Light-Driven Photocatalytic Hydrogenation of Olefins Using Water as the H Source
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In this work, a highly efficient PCN-KCl (KCl-modified polymeric carbon nitride) nanosheet photocatalyst was synthesized with the assistance of KCl. The as-prepared PCN-KCl catalyst shows a more than 30-fold enhancement in the photocatalytic activity for H2 evolution from water compared to the pristine PCN. More importantly, when PCN-KCl was composited with a second catalyst (Pd nanoparticles), the simultaneous production and utilization of active H species for alkenes hydrogenation was achieved by visible light irradiation under ambient conditions.
- Fan, Xin,Yao, Yanling,Xu, Yangsen,Yu, Lei,Qiu, Chuntian
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p. 2596 - 2599
(2019/05/10)
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- Iridium-Catalyzed Alkene-Selective Transfer Hydrogenation with 1,4-Dioxane as Hydrogen Donor
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The iridium-catalyzed transfer hydrogenation of alkenes using 1,4-dioxane as a hydrogen donor is described. The use of 1,2-bis(dicyclohexylphosphino)ethane (DCyPE), featuring bulky and highly electron-donating properties, led to high catalytic activity. A polystyrene-cross-linking bisphosphine PS-DPPBz produced a reusable heterogeneous catalyst. These homogeneous and heterogeneous protocols achieved chemoselective transfer hydrogenation of alkenes over other potentially reducible functional groups such as carbonyl, nitro, cyano, and imino groups in the same molecule.
- Zhang, Deliang,Iwai, Tomohiro,Sawamura, Masaya
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supporting information
p. 5867 - 5872
(2019/08/26)
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- Electrochemical Hydrogenation with Gaseous Ammonia
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As a carbon-free and sustainable fuel, ammonia serves as high-energy-density hydrogen-storage material. It is important to develop new reactions able to utilize ammonia as a hydrogen source directly. Herein, we report an electrochemical hydrogenation of alkenes, alkynes, and ketones using ammonia as the hydrogen source and carbon electrodes. A variety of heterocycles and functional groups, including for example sulfide, benzyl, benzyl carbamate, and allyl carbamate were well tolerated. Fast stepwise electron transfer and proton transfer processes were proposed to account for the transformation.
- Li, Jin,He, Lingfeng,Liu, Xu,Cheng, Xu,Li, Guigen
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supporting information
p. 1759 - 1763
(2019/01/16)
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- Supported Cobalt Nanoparticles for Hydroformylation Reactions
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Hydroformylation of olefins has been studied in the presence of specific heterogeneous cobalt nanoparticles. The catalytic materials were prepared by pyrolysis of preformed cobalt complexes deposited onto different inorganic supports. Atomic absorption spectroscopy (AAS) measurements indicated a correlation of catalyst activity and cobalt leaching as well as a strong influence of the heterogeneous support on the productivity. These new, low-cost, easy-to-handle catalysts can substitute more toxic, unstable and volatile cobalt carbonyl complexes for hydroformylations on a laboratory scale.
- Hertrich, Maximilian Franz,Scharnagl, Florian Korbinian,Pews-Davtyan, Anahit,Kreyenschulte, Carsten Robert,Lund, Henrik,Bartling, Stephan,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 5534 - 5538
(2019/03/26)
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- Transfer Hydrocyanation of α- and α,β-Substituted Styrenes Catalyzed by Boron Lewis Acids
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A straightforward gram-scale preparation of cyclohexa-1,4-diene-based hydrogen cyanide (HCN) surrogates is reported. These are bench-stable but formally release HCN and rearomatize when treated with Lewis acids. For BCl3, the formation of the isocyanide adduct [(CN)BCl3]? and the corresponding Wheland complex was verified by mass spectrometry. In the presence of 1,1-di- and trisubstituted alkenes, transfer of HCN from the surrogate to the C?C double bond occurs, affording highly substituted nitriles with Markovnikov selectivity. The success of this transfer hydrocyanation depends on the Lewis acid employed; catalytic amounts of BCl3 and (C6F5)2BCl are shown to be effective while B(C6F5)3 and BF3?OEt2 are not.
- Orecchia, Patrizio,Yuan, Weiming,Oestreich, Martin
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supporting information
p. 3579 - 3583
(2019/02/05)
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- Ni(NIXANTPHOS)-Catalyzed Mono-Arylation of Toluenes with Aryl Chlorides and Bromides
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A nickel-catalyzed cross-coupling of toluene derivatives with both aryl bromides and chlorides using a NIXANTPHOS-ligated nickel(II) complex has been developed. The key factor to success is proposed to be the catalyst activation of toluene by a cation-π complex, enabling methyl arenes (pKa ≈ 43) to be deprotonated with the relatively mild base NaN(SiMe3)2. This method facilitates access to a variety of sterically and electronically diverse hetero- and nonheteroaryl-containing diarylmethanes.
- Jiang, Hui,Sha, Sheng-Chun,Jeong, Soo A,Manor, Brian C.,Walsh, Patrick J.
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supporting information
p. 1735 - 1739
(2019/03/20)
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- Super-Bulky Penta-arylcyclopentadienyl Ligands: Isolation of the Full Range of Half-Sandwich Heavy Alkaline-Earth Metal Hydrides
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Hydrogenolysis of the half-sandwich penta-arylcyclopentadienyl-supported heavy alkaline-earth-metal alkyl complexes (CpAr)Ae[CH(SiMe3)2](S) (CpAr=C5Ar5, Ar=3,5-iPr2-C6H3; S=THF or DABCO) in hexane afforded the calcium, strontium, and barium metal–hydride complexes as the same dimers [(CpAr)Ae(μ-H)(S)]2 (Ae=Ca, S=THF, 2-Ca; Ae=Sr, Ba, S=DABCO, 4-Ae), which were characterized by NMR spectroscopy and single-crystal X-ray analysis. 2-Ca, 4-Sr, and 4-Ba catalyzed alkene hydrogenation under mild conditions (30 °C, 6 atm, 5 mol % cat.), with the activity increasing with the metal size. A variety of activated alkenes including tri- and tetra-substituted olefins, semi-activated alkene (Me3SiCH=CH2), and unactivated terminal alkene (1-hexene) were evaluated.
- Shi, Xianghui,Qin, Guorui,Wang, Yang,Zhao, Lanxiao,Liu, Zhizhou,Cheng, Jianhua
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supporting information
p. 4356 - 4360
(2019/02/25)
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- Bioinspired Metal-Free Formal Decarbonylation of α-Branched Aliphatic Aldehydes at Ambient Temperature
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A sequence of a Baeyer–Villiger oxidation and a Lewis acid-promoted reduction of the resulting formate with Et3SiH enabled the metal-free formal decarbonylation of tertiary and secondary aliphatic aldehydes. The new methodology mimics the biosynthetic decarbonylation pathway through oxidative C?C bond cleavage rather than the C(O)?H bond activation known from conventional Tsuji–Wilkinson-type reactions. The substrate scope is complementary to existing transition-metal-catalyzed protocols.
- Richter, Sven C.,Oestreich, Martin
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supporting information
p. 8508 - 8512
(2019/06/04)
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- Catalytic protodeboronation of pinacol boronic esters: Formal anti-Markovnikov hydromethylation of alkenes
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Pinacol boronic esters are highly valuable building blocks in organic synthesis. In contrast to the many protocols available on the functionalizing deboronation of alkyl boronic esters, protodeboronation is not well developed. Herein we report catalytic protodeboronation of 1°, 2° and 3° alkyl boronic esters utilizing a radical approach. Paired with a Matteson-CH2-homologation, our protocol allows for formal anti-Markovnikov alkene hydromethylation, a valuable but unknown transformation. The hydromethylation sequence was applied to methoxy protected (-)-Δ8-THC and cholesterol. The protodeboronation was further used in the formal total synthesis of δ-(R)-coniceine and indolizidine 209B.
- Clausen, Florian,Kischkewitz, Marvin,Bergander, Klaus,Studer, Armido
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p. 6210 - 6214
(2019/06/27)
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- Method for synthesizing succinic acid compounds
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The invention provides a method for synthesizing succinic acid compounds. The method specifically comprises the following steps: adding a substrate, a photocatalyst and an alkali into a reaction tube,adding a reducing agent and a solvent under the atmosphere of CO2, conducting reacting under the irradiation of visible light, carrying out quenching treatment after the raw materials react completely, and then conducting separating and purifying to obtain a dicarboxylated product of olefin, namely a succinic acid compound. The photocatalyst is 4CzIPN or Ir[(ppy)2(dtbppy)]PF6 and the like, and the reaction substrate comprises 1,1-diaryl ethylene, a monoaryl substituted olefin compound, an acrylate compound and allene. According to the scheme provided by the invention, the reaction conditionsare mild, the applicability of the reaction substrate is wide, and the yield is basically not influenced under the condition that the reaction substrate is amplified to the gram scale; and meanwhile,the invention overcomes the defects of high toxicity of reagents and harsh reaction conditions in the prior art, and has a good industrial application prospect.
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Paragraph 0054
(2019/08/01)
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- Hydrogenolysis of C?O Chemical Bonds of Broad Scope Mediated by a New Spherical Sol–Gel Catalyst
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The new spherical sol–gel hybrid material SiliaCat Pd0 selectively mediates the hydrogenolysis of aromatic alcohols, aldehydes, and ketones by using an ultralow catalytic amount (0.1 mol % Pd) under mild reaction conditions. The broad reaction scope as well as the catalyst's superior activity and pronounced stability open the route to green and convenient reductive deoxygenation processes of primary synthetic relevance in chemical research as well as in the fine chemical and petrochemical industries.
- Pandarus, Valerica,Ciriminna, Rosaria,Gingras, Geneviève,Béland, Fran?ois,Pagliaro, Mario,Kaliaguine, Serge
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- Homogeneous Palladium-Catalyzed Transfer Hydrogenolysis of Benzylic Alcohols Using Formic Acid as Reductant
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We report the first homogeneous palladium-based transfer hydrogenolysis of benzylic alcohols using an in situ formed palladium-phosphine complex and formic acid as reducing agent. The reaction requires a catalyst loading as low as only 1 mol % of palladium and just a slight excess of reductant to obtain the deoxygenated alkylarenes in good to excellent yields. Besides demonstrating the broad applicability for primary, secondary and tertiary benzylic alcohols, a reaction intermediate could be identified. Additionally, it could be shown that partial oxidation of the applied phosphine ligand was beneficial for the course of the reaction, presumably by stabilizing the active catalyst. Reaction profiles and catalyst poisoning experiments were used to characterize the catalyst, the results of which indicate a homogeneous metal complex as the active species.
- Ciszek, Benjamin,Fleischer, Ivana
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supporting information
p. 12259 - 12263
(2018/08/28)
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- Transfer Hydrogenation of Alkenes Using Ethanol Catalyzed by a NCP Pincer Iridium Complex: Scope and Mechanism
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The first general catalytic approach to effecting transfer hydrogenation (TH) of unactivated alkenes using ethanol as the hydrogen source is described. A new NCP-type pincer iridium complex (BQ-NCOP)IrHCl containing a rigid benzoquinoline backbone has been developed for efficient, mild TH of unactivated C-C multiple bonds with ethanol, forming ethyl acetate as the sole byproduct. A wide variety of alkenes, including multisubstituted alkyl alkenes, aryl alkenes, and heteroatom-substituted alkenes, as well as O- or N-containing heteroarenes and internal alkynes, are suitable substrates. Importantly, the (BQ-NCOP)Ir/EtOH system exhibits high chemoselectivity for alkene hydrogenation in the presence of reactive functional groups, such as ketones and carboxylic acids. Furthermore, the reaction with C2D5OD provides a convenient route to deuterium-labeled compounds. Detailed kinetic and mechanistic studies have revealed that monosubstituted alkenes (e.g., 1-octene, styrene) and multisubstituted alkenes (e.g., cyclooctene (COE)) exhibit fundamental mechanistic difference. The OH group of ethanol displays a normal kinetic isotope effect (KIE) in the reaction of styrene, but a substantial inverse KIE in the case of COE. The catalysis of styrene or 1-octene with relatively strong binding affinity to the Ir(I) center has (BQ-NCOP)IrI(alkene) adduct as an off-cycle catalyst resting state, and the rate law shows a positive order in EtOH, inverse first-order in styrene, and first-order in the catalyst. In contrast, the catalysis of COE has an off-cycle catalyst resting state of (BQ-NCOP)IrIII(H)[O(Et)···HO(Et)···HOEt] that features a six-membered iridacycle consisting of two hydrogen-bonds between one EtO ligand and two EtOH molecules, one of which is coordinated to the Ir(III) center. The rate law shows a negative order in EtOH, zeroth-order in COE, and first-order in the catalyst. The observed inverse KIE corresponds to an inverse equilibrium isotope effect for the pre-equilibrium formation of (BQ-NCOP)IrIII(H)(OEt) from the catalyst resting state via ethanol dissociation. Regardless of the substrate, ethanol dehydrogenation is the slow segment of the catalytic cycle, while alkene hydrogenation occurs readily following the rate-determining step, that is, β-hydride elimination of (BQ-NCOP)Ir(H)(OEt) to form (BQ-NCOP)Ir(H)2 and acetaldehyde. The latter is effectively converted to innocent ethyl acetate under the catalytic conditions, thus avoiding the catalyst poisoning via iridium-mediated decarbonylation of acetaldehyde.
- Wang, Yulei,Huang, Zhidao,Leng, Xuebing,Zhu, Huping,Liu, Guixia,Huang, Zheng
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supporting information
p. 4417 - 4429
(2018/04/05)
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- Olefin-Stabilized Cobalt Nanoparticles for C=C, C=O, and C=N Hydrogenations
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The development of cobalt catalysts that combine easy accessibility and high selectivity constitutes a promising approach to the replacement of noble-metal catalysts in hydrogenation reactions. This report introduces a user-friendly protocol that avoids complex ligands, hazardous reductants, special reaction conditions, and the formation of highly unstable pre-catalysts. Reduction of CoBr2 with LiEt3BH in the presence of alkenes led to the formation of hydrogenation catalysts that effected clean conversions of alkenes, carbonyls, imines, and heteroarenes at mild conditions (3 mol % cat., 2–10 bar H2, 20–80 °C). Poisoning studies and nanoparticle characterization by TEM, EDX, and DLS supported the notion of a heterotopic catalysis mechanism.
- Sandl, Sebastian,Schwarzhuber, Felix,P?llath, Simon,Zweck, Josef,Jacobi von Wangelin, Axel
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supporting information
p. 3403 - 3407
(2018/02/13)
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- Catalytic Use of Low-Valent Cationic Gallium(I) Complexes as π-Acids
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Transformations of alkene and alkyne substrates relevant to π-Lewis acid catalysis have been performed using low-valent Ga(I) species for the first time. [Ga(I)(PhF)2]+[Al(ORF)4]? and gallium dichloride (i. e. [Ga(I)]+[GaCl4]?) proved to be efficient catalysts for cycloisomerizations, Friedel-Crafts reactions, transfer hydrogenations, and reductive hydroarylations. Their activity is compared to more common Ga(III) complexes. This study shows that even the readily available and yet overlooked gallium dichloride salt can be a more active π-Lewis acid catalyst than gallium trichloride or other Ga(III) species. (Figure presented.).
- Li, Zhilong,Thiery, Guillaume,Lichtenthaler, Martin R.,Guillot, Régis,Krossing, Ingo,Gandon, Vincent,Bour, Christophe
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supporting information
p. 544 - 549
(2017/11/27)
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- Application of Silicon-Initiated Water Splitting for the Reduction of Organic Substrates
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The use of water as a donor for hydrogen suitable for the reduction of several important classes of organic compounds is described. It is found that the reductive water splitting can be promoted by several metalloids among which silicon shows the best efficiency. The developed methodologies were applied for the reduction of nitro compounds, N-oxides, sulfoxides, alkenes, alkynes, hydrodehalogenation as well as for the gram-scale synthesis of several substrates of industrial importance.
- Gevorgyan, Ashot,Mkrtchyan, Satenik,Grigoryan, Tatevik,Iaroshenko, Viktor O.
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p. 375 - 382
(2018/06/04)
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- Stainless Steel-Mediated Hydrogen Generation from Alkanes and Diethyl Ether and Its Application for Arene Reduction
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Hydrogen gas can be generated from simple alkanes (e.g., n-pentane, n-hexane, etc.) and diethyl ether (Et2O) by mechanochemical energy using a planetary ball mill (SUS304, Fritsch Pulverisette 7), and the use of stainless steel balls and vessel is an important factor to generate the hydrogen. The reduction of organic compounds was also accomplished using the in-situ-generated hydrogen. While the use of pentane as the hydrogen source facilitated the reduction of the olefin moieties, the arene reduction could proceed using Et2O. Within the components (Fe, Cr, Ni, etc.) of the stainless steel, Cr was the metal factor for the hydrogen generation from the alkanes and Et2O, and Ni metal played the role of the hydrogenation catalyst.
- Sawama, Yoshinari,Yasukawa, Naoki,Ban, Kazuho,Goto, Ryota,Niikawa, Miki,Monguchi, Yasunari,Itoh, Miki,Sajiki, Hironao
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supporting information
p. 2892 - 2896
(2018/05/29)
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- Base-Free Generation of Organic Electron Donors from Air-Stable Precursors
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Organic electron donors (OEDs) are powerful reducing agents recognized for their potential in the reduction of challenging substrates and in original applications. Nonetheless, their low stability in atmospheric oxygen or over time complicates their manipulation and storage. To overcome these constraints and enhance OED practicality, new air- and moisture-stable aminopyridinium carboxylate and carbonate precursors were synthesized and thermally activated to generate the potent electron donor in situ. Carboxylate adducts proved to be excellent latent OED systems, enabling the facile and efficient reduction of challenging substrates. Their reduction properties were correlated to their structural characteristics by thermogravimetric and spectroscopic analysis.
- Tintori, Guillaume,Nabokoff, Pierre,Buhaibeh, Ruqaya,Bergé-Lefranc, David,Redon, Sébastien,Broggi, Julie,Vanelle, Patrice
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supporting information
p. 3148 - 3153
(2018/03/13)
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