- Selective C-C bonds formation, N-alkylation and benzo[d]imidazoles synthesis by a recyclable zinc composite
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Earth abundant metals are much less expensive, promising, valuable metals and could be served as catalysts for the borrowing hydrogen reaction, dehydrogenation and heterocycles synthesis, instead of noble metals. The uniformly dispersed zinc composites were designed, synthesized and carefully characterized by means of XPS, EDS, TEM and XRD. The resulting zinc composite showed good catalytic activity for the N-alkylation of amines with amines, ketones with alcohols in water under base-free conditions, while unsaturated carbonyl compounds could also be synthesized by tuning the reaction conditions. Importantly, it was the first time to realize the synthesis of 2-aryl-1H-benzo[d]imidazole derivatives by using this zinc composite under green conditions. Meanwhile, this zinc catalyst could be easily recovered and reused for at least five times.
- Zhu, Guanxin,Duan, Zheng-Chao,Zhu, Haiyan,Ye, Dongdong,Wang, Dawei
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supporting information
p. 266 - 270
(2021/08/06)
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- BTP-Rh@g-C3N4 as an efficient recyclable catalyst for dehydrogenation and borrowing hydrogen reactions
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Highly active catalysts play an important role in modern catalysis. A novel and efficient ligand benzotriazole-pyrimidine (BTP) and the corresponding rhodium composite on C3N4 were successfully synthesized. The resulting rhodium composite was fully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), thermogravimetric analysis (TGA), and x-ray photoelectron spectroscopy (XPS). The obtained composite exhibited good catalytic activity and good recovery performance in the synthesis of quinoxaline from 2-aminobenzyl alcohol and benzonitrile, and more than 20 quinoxalines were obtained in good yields. Additionally, it also showed that rhodium composite could achieved good catalytic performance in the synthesis of functionalized ketone through borrowing hydrogen strategy.
- Luo, Lan,Liu, Hongqiang,Zeng, Wei,Hu, Wenkang,Wang, Dawei
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- Nickel-catalyzed α-alkylation of ketones with benzyl alcohols
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We reported an efficient method for α-alkylation of ketones with benzyl alcohols using the pyridine-bridged pincer-type N-heterocyclic carbenes nickel complexes as catalysts. A wide range of ketones and benzyl alcohols were efficiently converted into various alkylated products in moderate to high yields. In addition, these nickel complexes were also successfully applied for the synthesis of a wide range of quinoline derivatives.
- Wu, Di,Wang, Yubin,Li, Min,Shi, Lei,Liu, Jichang,Liu, Ning
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- Nickel-Mediated Photoreductive Cross Coupling of Carboxylic Acid Derivatives for Ketone Synthesis**
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A simple visible light photochemical, nickel-catalyzed synthesis of ketones from carboxylic acid-derived precursors is presented. Hantzsch ester (HE) functions as a cheap, green and strong photoreductant to facilitate radical generation and also engages in the Ni-catalytic cycle to restore the reactive species. With this dual role, HE allows for the coupling of a large variety of radicals (1°,2°, benzylic, α-oxy & α-amino) with aroyl and alkanoyl moieties, a new feature in reactions of this type. With both precursors deriving from abundant carboxylic acids, this protocol is a welcome addition to the organic chemistry toolbox. The reaction proceeds under mild conditions without the need for toxic metal reagents or bases and shows a wide scope, including pharmaceuticals and complex molecular architectures.
- Brauer, Jan,Quraishi, Elisabeth,Kammer, Lisa Marie,Opatz, Till
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supporting information
p. 18168 - 18174
(2021/11/30)
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- Synthesis of α-Alkylated Ketones via Selective Epoxide Opening/Alkylation Reactions with Primary Alcohols
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A new method for converting terminal epoxides and primary alcohols into α-alkylated ketones under borrowing hydrogen conditions is reported. The procedure involves a one-pot epoxide ring opening and alkylation via primary alcohols in the presence of an N-heterocyclic carbene iridium(I) catalyst, under aerobic conditions, with water as the side product.
- Gen?, Serta?,Gülcemal, Süleyman,Günnaz, Salih,?etinkaya, Bekir,Gülcemal, Derya
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supporting information
p. 5229 - 5234
(2021/07/19)
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- Borane-Catalyzed, Chemoselective Reduction and Hydrofunctionalization of Enones Enabled by B-O Transborylation
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The use of stoichiometric organoborane reductants in organic synthesis is well established. Here these reagents have been rendered catalytic through an isodesmic B-O/B-H transborylation applied in the borane-catalyzed, chemoselective alkene reduction and formal hydrofunctionalization of enones. The reaction was found to proceed by a 1,4-hydroboration of the enone and B-O/B-H transborylation with HBpin, enabling catalyst turnover. Single-turnover and isotopic labeling experiments supported the proposed mechanism of catalysis with 1,4-hydroboration and B-O/B-H transborylation as key steps.
- Nicholson, Kieran,Langer, Thomas,Thomas, Stephen P.
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supporting information
p. 2498 - 2504
(2021/04/13)
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- Iridium Complexes as Efficient Catalysts for Construction of α-Substituted Ketones via Hydrogen Borrowing of Alcohols in Water
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Ketones are of great importance in synthesis, biology, and pharmaceuticals. This paper reports an iridium complexes-catalyzed cross-coupling of alcohols via hydrogen borrowing, affording a series of α-alkylated ketones in high yield (86 %–95 %) and chemoselectivities (>99 : 1). This methodology has the advantages of low catalyst loading (0.1 mol%) and environmentally benign water as the solvent. Studies have shown the amount of base has a great impact on chemoselectivities. Meanwhile, deuteration experiments show water plays an important role in accelerating the reduction of the unsaturated ketones intermediates. Remarkably, a gram-scale experiment demonstrates this methodology of iridium-catalyzed cross-coupling of alcohols has potential application in the practical synthesis of α-alkylated ketones.
- Luo, Nianhua,Zhong, Yuhong,Wen, Huiling,Shui, Hongling,Luo, Renshi
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p. 1355 - 1364
(2021/03/03)
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- A Proton-Responsive Pyridyl(benzamide)-Functionalized NHC Ligand on Ir Complex for Alkylation of Ketones and Secondary Alcohols
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A Cp*Ir(III) complex (1) of a newly designed ligand L1 featuring a proton-responsive pyridyl(benzamide) appended on N-heterocyclic carbene (NHC) has been synthesized. The molecular structure of 1 reveals a dearomatized form of the ligand. The protonation of 1 with HBF4 in tetrahydrofuran gives the corresponding aromatized complex [Cp*Ir(L1H)Cl]BF4 (2). Both compounds are characterized spectroscopically and by X-ray crystallography. The protonation of 1 with acid is examined by 1H NMR and UV-vis spectra. The proton-responsive character of 1 is exploited for catalyzing α-alkylation of ketones and β-alkylation of secondary alcohols using primary alcohols as alkylating agents through hydrogen-borrowing methodology. Compound 1 is an effective catalyst for these reactions and exhibits a superior activity in comparison to a structurally similar iridium complex [Cp*Ir(L2)Cl]PF6 (3) lacking a proton-responsive pendant amide moiety. The catalytic alkylation is characterized by a wide substrate scope, low catalyst and base loadings, and a short reaction time. The catalytic efficacy of 1 is also demonstrated for the syntheses of quinoline and lactone derivatives via acceptorless dehydrogenation, and selective alkylation of two steroids, pregnenolone and testosterone. Detailed mechanistic investigations and DFT calculations substantiate the role of the proton-responsive ligand in the hydrogen-borrowing process.
- Kaur, Mandeep,U Din Reshi, Noor,Patra, Kamaless,Bhattacherya, Arindom,Kunnikuruvan, Sooraj,Bera, Jitendra K.
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supporting information
p. 10737 - 10748
(2021/06/15)
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- Visible-Light-Promoted Photocatalyst-Free Hydroacylation and Diacylation of Alkenes Tuned by NiCl2·DME
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Herein, we describe a visible light-promoted hydroacylation strategy that facilitates the preparation of ketones from alkenes and 4-acyl-1,4-dihydropyridines via an acyl radical addition and hydrogen atom transfer pathway under photocatalyst-free conditions. The efficiency was highlighted by wide substrate scope, good to high yields, successful scale-up experiments, and expedient preparation of highly functionalized ketone derivatives. In addition, this protocol allows for the synthesis of 1,4-dicarbonyl compounds through alkene diacylation in the presence of NiCl2·DME.
- Zhao, Xinxin,Li, Bing,Xia, Wujiong
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p. 1056 - 1061
(2020/02/15)
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- Transition metal complexes of a bis(carbene) ligand featuring 1,2,4-triazolin-5-ylidene donors: structural diversity and catalytic applications
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Dialkylation of the 1,3-bis(1,2,4-triazol-1-yl)benzene with ethyl bromide results in the formation of [L-H2]Br2which, upon salt metathesis with NH4PF6, readily yields the bis(triazolium) salt [L-H2](PF6)2with non-coordinating counterions. [L-H2](PF6)2and Ag2O react in a 1?:?1 ratio to yield a binuclear AgI-tetracarbene complex of the composition [(L)2Ag2](PF6)2which undergoes a facile transmetalation reaction with [Cu(SMe2)Br] to deliver the corresponding CuI-NHC complex [(L)2Cu2](PF6)2. In contrast, the [L-H2]Br2reacts with [Ir(Cp*)Cl2]2to generate a doubly C-H activated IrIII-NHC complex5. Similarly, the triazolinylidene donor supported diorthometalated RuII-complex6is also obtained. Complexes5and6represent the first examples of a stable diorthometalated binuclear IrIII/RuII-complex supported by 1,2,4-triazolin-5-ylidene donors. The synthesized IrIII-NHC complex5is found to be more effective than its RuII-analogue (6) for the reduction of a range of alkenes/alkynesviathe transfer hydrogenation strategy. Conversely, RuII-complex6is identified as an efficient catalyst (0.01 mol% loading) for the β-alkylation of a wide range of secondary alcohols using primary alcohols as alkylating partnersviaa borrowing hydrogen strategy.
- Donthireddy, S. N. R.,Illam, Praseetha Mathoor,Rit, Arnab,Singh, Vivek Kumar
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p. 11958 - 11970
(2020/09/21)
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- Alkylation synthesis method of in-situ catalytic alcohol (by machine translation)
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The method comprises VIB metal complexes, an auxiliary ligand and a base as a catalytic reaction system, wherein the alcohol serves as an alkylating agent, and the nucleophilic substrate is subjected to in-situ catalytic alkylation reaction in a solvent and an inert gas atmosphere. The catalytic system has a wide application range on a substrate, can catalyze the synthesis of C-N and C-C bond compounds of different structures under mild conditions, and can green synthesize a series of valuable N - alkylation and C - alkylation compounds. (by machine translation)
- -
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Paragraph 0099-0101; 0129-0131
(2020/11/01)
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- Tuning the Product Selectivity of the α-Alkylation of Ketones with Primary Alcohols using Oxidized Titanium Nitride Photocatalysts and Visible Light
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The direct α-alkylation of ketones with alcohol to synthesize important α-alkylated ketones and enones is an attractive procedure for C-C bond formation. High reaction temperatures are always needed for heterogeneous catalysis using non-noble metals, and switching product selectivity in one catalysis system remains a great challenge. In the present study, a visible-light-driven procedure for this reaction is proposed, using oxidized TiN photocatalysts under mild conditions, whereby the product selectivity can be well-tuned. Oxidized TiN photocatalysts with tunable surface N/O ratios were successfully synthesized through the facile and flexible thermal oxidation treatment of low-cost TiN nanopowder. The α-alkylation of acetophenone with benzyl alcohol to form the two important compounds chalcone and dihydrochalcone occurred even at room temperature and almost complete conversion was achieved at 100 °C under visible light. The proportion of the two products can be well-tuned by switching the surface N/O ratio of the synthesized photocatalysts. Visible light is demonstrated to affect the surface N/O ratio of the photocatalysts and contribute to tuning the product selectivity. Light intensity and action spectrum study proves that the generation of energetic charge carriers results in the observed activities under visible light, based on interband transitions of TiN or the ligand-to-metal charge transfer (LMCT) effect of the surface complex formed on TiO2. Thermal energy can be coupled with light energy within this photocatalytic system, which will facilitate the full use of solar energy. Different sequential reaction mechanisms on TiN and TiO2 are proposed to be responsible for the tunable product selectivity. The wide reaction scope, the fine conversion at a low light intensity, and the favorable reusability of photocatalysts prove the great application potential of this visible-light-driven procedure for the α-alkylation of ketones with primary alcohols.
- Li, Peifeng,Su, Haijia,Xiao, Gang,Zhao, Yilin
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p. 3640 - 3649
(2020/04/09)
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- Method for preparing alpha-alkyl substituted ketone compound
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The invention relates to a method for preparing an alpha-alkyl substituted ketone compound, which comprises the following steps: preparing a primary alcohol compound and a secondary alcohol compound as raw materials, adding alkali; with a cyclic iridium complex as a catalyst and water as a reaction medium, heating and stirring the mixture and reacting for 10 to 24 hours under the protection of inert gas, and cooling a reaction product to room temperature after the reaction is finished; carrying out reduced pressure distillation and concentration to obtain a crude product, and carrying out column chromatography purification to obtain a series of alpha alkyl substituted ketone compounds. The method is simple to operate, available in raw materials, low in price, high in reaction efficiency and selectivity, good in adaptability to various functional groups and wide in substrate universality; since water is used as a reaction medium to meet the green and environment-friendly requirements, the method is environmentally friendly and is carried out at gram level, so that the potential of industrially synthesizing the alpha alkyl substituted ketone compound is achieved; therefore, The method has expanded application in the fields of medicines, organic synthesis and the like.
- -
-
Paragraph 0125-0132
(2020/12/29)
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- Sustainable and Selective Alkylation of Deactivated Secondary Alcohols to Ketones by Non-bifunctional Pincer N-heterocyclic Carbene Manganese
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A sustainable and green route to access diverse functionalized ketones via dehydrogenative–dehydrative cross-coupling of primary and secondary alcohols is demonstrated. This borrowing hydrogen approach employing a pincer N-heterocyclic carbene Mn complex displays high activity and selectivity. A variety of primary and secondary alcohols are well tolerant and result in satisfactory isolated yields. Mechanistic studies suggest that this reaction proceeds via a direct outer-sphere mechanism and the dehydrogenation of the secondary alcohol substrates plays a vital role in the rate-limiting step.
- Lan, Xiao-Bing,Ye, Zongren,Liu, Jiahao,Huang, Ming,Shao, Youxiang,Cai, Xiang,Liu, Yan,Ke, Zhuofeng
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p. 2557 - 2563
(2020/05/04)
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- Chemoselective Hydrosilylation of the α,β-Site Double Bond in α,β- And α,β,γ,δ-Unsaturated Ketones Catalyzed by Macrosteric Borane Promoted by Hexafluoro-2-propanol
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The B(C6F5)3-catalyzed chemoselective hydrosilylation of α,β- and α,β,γ,δ-unsaturated ketones into the corresponding non-symmetric ketones in mild reaction conditions is developed. Nearly 55 substrates including those bearing reducible functional groups such as alkynyl, alkenyl, cyano, and aromatic heterocycles are chemoselectively hydrosilylated in good to excellent yields. Isotope-labeling studies revealed that hexafluoro-2-propanol also served as a hydrogen source in the process.
- Zhan, Xiao-Yu,Zhang, Hua,Dong, Yu,Yang, Jian,He, Shuai,Shi, Zhi-Chuan,Tang, Lei,Wang, Ji-Yu
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p. 6578 - 6592
(2020/07/17)
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- Method for synthesizing alpha-alkylated ketone in water
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The invention discloses a method for synthesizing alpha-alkylated ketone in water. The method comprises the following steps: adding ketone, compound alcohol, a transition metal iridium catalyst, an alkali and a solvent, namely water into a reaction container, carrying out a reflux reaction on a reaction mixture in the air for several hours, carrying out cooling to room temperature, carrying out rotary evaporation to remove the solvent, and carrying out column separation (ethyl acetate/petroleum ether) to obtain a target compound, namely alpha-alkylated ketone. A reaction equivalent substrate is used in the reaction process, so raw material waste is avoided; equivalent alkali is used, so better environmental protection performance is obtained; water reflux reaction conditions are milder; and non-toxic and harmless pure water is used as the solvent in the reaction, only water is generated as a by-product, so atom reaction economy is high, and the requirements of green chemistry are met.
- -
-
Paragraph 0082-0086
(2020/08/22)
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- Cyclometalated Ruthenium Pincer Complexes as Catalysts for the α-Alkylation of Ketones with Alcohols
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Ruthenium PNP pincer complexes bearing supplementary cyclometalated C,N-bound ligands have been prepared and fully characterized for the first time. By replacing CO and H? as ancillary ligands in such complexes, additional electronic and steric modifications of this topical class of catalysts are possible. The advantages of the new catalysts are demonstrated in the general α-alkylation of ketones with alcohols following a hydrogen autotransfer protocol. Herein, various aliphatic and benzylic alcohols were applied as green alkylating agents for ketones bearing aromatic, heteroaromatic or aliphatic substituents as well as cyclic ones. Mechanistic investigations revealed that during catalysis, Ru carboxylate complexes are predominantly formed whereas neither the PNP nor the CN ligand are released from the catalyst in significant amounts.
- Piehl, Patrick,Amuso, Roberta,Alberico, Elisabetta,Junge, Henrik,Gabriele, Bartolo,Neumann, Helfried,Beller, Matthias
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supporting information
p. 6050 - 6055
(2020/03/13)
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- Proton-Coupled Electron Transfer: Transition-Metal-Free Selective Reduction of Chalcones and Alkynes Using Xanthate/Formic Acid
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Highly chemoselective reduction of α,β-unsaturated ketones to saturated ketones and stereoselective reduction of alkynes to (E)-alkenes has been developed under a transition-metal-free condition using a xanthate/formic acid mixture through proton-coupled electron transfer (PCET). Mechanistic experiments and DFT calculations support the possibility of a concerted proton electron-transfer (CPET) pathway. This Birch-type reduction demonstrates that a small nucleophilic organic molecule can be used as a single electron-transfer (SET) reducing agent with a proper proton source.
- Prasanna, Ramanathan,Guha, Somraj,Sekar, Govindasamy
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p. 2650 - 2653
(2019/04/17)
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- Reaction condition controlled nickel(ii)-catalyzed C-C cross-coupling of alcohols
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The challenge in the C-C cross-coupling of secondary and primary alcohols using acceptorless dehydrogenation coupling (ADC) is the difficulty in accurately controlling product selectivities. Herein, we report a controlled approach to a diverse range of β-alkylated secondary alcohols, α-alkylated ketones and α,β-unsaturated ketones using the ADC methodology employing a Ni(ii) 4,6-dimethylpyrimidine-2-thiolate cluster catalyst under different reaction conditions. This catalyst could tolerate a wide range of substrates and exhibited a high activity for the annulation reaction of secondary alcohols with 2-aminobenzyl alcohols to yield quinolines. This work is an example of precise chemoselectivity control by careful choice of reaction conditions.
- Zhang, Meng-Juan,Li, Hong-Xi,Young, David J.,Li, Hai-Yan,Lang, Jian-Ping
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supporting information
p. 3567 - 3574
(2019/04/14)
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- Ligand-controlled phosphine-free Co(II)-catalysed cross-coupling of secondary and primary alcohols
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Cobalt(II) complexes (5 mol% Co) bearing phosphine-free N?N?N pincer ligands efficiently catalyze C–C coupling of secondary and primary alcohols to selectively form α-alkylated ketones with a good functional group compatibility using NaOH (20 mol%) as a base at 120 °C. The NH group on the N?N?N–Co(II) precatalyst controls the activity and selectivity. This simple catalytic system is involved in the synthesis of quinolones via the dehydrogenative annulation of 2-aminobenzyl alcohols with secondary alcohols.
- Zhang, Shi-Qi,Guo, Bin,Xu, Ze,Li, Hong-Xi,Li, Hai-Yan,Lang, Jian-Ping
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- Cobalt-Catalyzed Chemoselective Transfer Hydrogenation of C=C and C=O Bonds with Alkanols
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An environmentally benign protocol of chemoselective transfer hydrogenation of C=C and C=O bonds with alkanols under base-free conditions is developed by this study, wherein the cobalt- bidentate phosphine catalyst precursor is commercially available and
- Jiang, Biao-Lin,Ma, Shuang-Shuang,Wang, Meng-Liang,Liu, Dian-Sheng,Xu, Bao-Hua,Zhang, Suo-Jiang
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p. 1701 - 1706
(2019/03/08)
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- Chemoselective transfer hydrogenation of Α,Β-unsaturated carbonyls catalyzed by a reusable supported Pd nanoparticles on biomass-derived carbon
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We herein report highly chemoselective transfer hydrogenation of α,β-unsaturated carbonyl compounds to saturated carbonyls with formic acid as a hydrogen donor over a stable and recyclable heterogeneous Pd nanoparticles (NPs) on N,O-dual doped hierarchical porous biomass-derived carbon. The synergistic effect between Pd NPs and incorporated heteroatoms on carbon plays a critical role on promoting the reaction efficiency. A series of α,β-aromatic and aliphatic unsaturated carbonyl compounds was selectively reduced to their corresponding saturated carbonyls in up to 97% isolated yields with good tolerance of various functional groups. In addition, the catalyst can be successively reused for at least 6 times without significant loss in reaction efficiency.
- Song, Tao,Duan, Yanan,Yang, Yong
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- Chemoselective Hydrogenation of α,β-Unsaturated Carbonyls Catalyzed by Biomass-Derived Cobalt Nanoparticles in Water
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Herein, we report highly chemoselective hydrogenation of α,β-unsaturated carbonyls to saturated carbonyls catalyzed by cobalt nanoparticles supported on the biomass-derived carbon from bamboo shoots with molecular hydrogen in water, which is the first prototype using a heterogeneous non-noble metal catalyst for such organic transformation as far as we know. The optimal cobalt nanocatalyst, CoOx@NC-800, manifested remarkable activity and selectivity for hydrogenation of C=C in α,β-unsaturated carbonyls under mild conditions. A broad set of α,β-aromatic and aliphatic unsaturated carbonyls were selectively reduced to their corresponding saturated carbonyls in up to 99 % yields with good tolerance of various functional groups. Meanwhile, a new straightforward one-pot cascade synthesis of saturated carbonyls was realized with high activity and selectivity via the cross-aldol condensation of ketones with aldehydes followed by selective hydrogenation. More importantly, this one-pot strategy is applicable for the expedient synthesis of Loureirin A, a versatile bioactive and medicinal molecule, from readily available starting materials, further highlighting the practical utility of the catalyst. In addition, the catalyst can be easily separated for successive reuses without significant loss in both activity and selectivity.
- Song, Tao,Ma, Zhiming,Yang, Yong
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p. 1313 - 1319
(2019/01/25)
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- The α-alkylation of ketones with alcohols in pure water catalyzed by a water-soluble Cp?Ir complex bearing a functional ligand
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A water-soluble dinuclear Cp?Ir complex bearing 4,4′,6,6′-tetrahydroxy-2,2′-bipyrimidine as a bridging ligand was found to be a highly effective catalyst for the α-alkylation of ketones with alcohols in pure water. In the presence of catalyst (0.5 mol%), a series of desirable products were obtained with high reaction economy under environmentally benign conditions. The importance of the hydroxy group in the ligand for catalytic hydrogen transfer was confirmed by mechanism experiments. Furthermore, the application of this catalytic system for the synthesis of a biologically active molecule donepezil in pure water has been accomplished. Notably, this research would facilitate the progress of C-C bond-forming reactions in water catalyzed by water-soluble metal-ligand bifunctional catalysts.
- Meng, Chong,Xu, Jing,Tang, Yawen,Ai, Yao,Li, Feng
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p. 14057 - 14065
(2019/09/18)
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- Nonbifunctional Outer-Sphere Strategy Achieved Highly Active α-Alkylation of Ketones with Alcohols by N-Heterocyclic Carbene Manganese (NHC-Mn)
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The unusual nonbifunctional outer-sphere strategy was successfully utilized in developing an easily accessible N-heterocyclic carbene manganese (NHC-Mn) system for highly active α-alkylation of ketones with alcohols. This system was efficient for a wide range of ketones and alcohols under mild reaction conditions, and also for the green synthesis of quinoline derivatives. The direct outer-sphere mechanism and the high activity of the present system demonstrate the potential of nonbifunctional outer-sphere strategy in catalyst design for acceptorless dehydrogenative transformations.
- Lan, Xiao-Bing,Ye, Zongren,Huang, Ming,Liu, Jiahao,Liu, Yan,Ke, Zhuofeng
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supporting information
p. 8065 - 8070
(2019/10/11)
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- BINAP-copper supported by hydrotalcite as an efficient catalyst for the borrowing hydrogen reaction and dehydrogenation cyclization under water or solvent-free conditions
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A BINAP-Cu system supported by hydrotalcite has been developed and proved to be a highly efficient catalyst for the atom-efficient and green borrowing hydrogen reaction and dehydrogenative cyclization. This BINAP-Cu complex supported by hydrotalcite is highly air-stable and can be recycled at least five times under solvent-free conditions. Notably, 1-benzyl-2-aryl-1H-benzo[d]imidazole derivatives could be synthesized from alcohols in only one step with water as the solvent for the first time. This provided a much greener and efficient catalytic method towards the synthesis of functionalized amines, ketones and 1-benzyl-2-aryl-1H-benzo[d]imidazole derivatives with high yields under water or solvent-free conditions.
- Xu, Zhaojun,Yu, Xiaoli,Sang, Xinxin,Wang, Dawei
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supporting information
p. 2571 - 2577
(2018/06/11)
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- Iridium(III)- benzoxazolyl and benzothiazolyl phosphine ligands catalyzed versatile alkylation reactions with alcohols and the synthesis of quinolines and indole
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A series of benzoxazolyl and benzothiazolyl phosphine ligands 4a-4g were synthesized and characterized, which prepared from commercially available 2-aminophenol/2-aminobenzenethiol and 2-bromobenzaldehyde via cyclization and phosphination. The representative ligands 4c and 4e were determined by single-crystal X-ray diffraction. The corresponding iridium complexes could be generated in situ when [Cp*IrCl2]2 (Cp* = pentamethylcyclopentadienyl) encountered ligands. The molecular structures of complexes 5c and 5e were crystallographically characterized. The dihedral angles of N (1)-C (1)-C (8)-C (9) showed an increasing twist compared with the corresponding ligand. The iridium (III) catalysts were screened, [Cp*IrCl2]2/4a proved to be the optimal catalyst, which exhibited efficient catalytic activity toward versatile alkylations including ketones, secondary alcohols and amines with primary alcohols. Additionally, the synthesis of quinolines from ketones with 2-aminobenzyl alcohol by intermolecular cyclization and indole from 2-(2-aminophenyl)ethanol by intramolecular cyclization were achieved under the optimized conditions.
- Huang, Shuang,Wu, Si-Peng,Zhou, Quan,Cui, He-Zhen,Hong, Xi,Lin, Yue-Jian,Hou, Xiu-Feng
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- NNN pincer Ru(II)-complex-catalyzed α-alkylation of ketones with alcohols
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A series of novel ruthenium(II) complexes supported by a symmetrical NNN ligand were prepared and fully characterized. These complexes exhibited good performance in transfer hydrogenation to form new C-C bonds using alcohols as the alkylating agents, generating water as the only byproduct. A broad range of substrates, including (hetero)aryl- or alkyl-ketones and alcohols, were well tolerated under the optimized conditions. Notably, α-substituted methylene ketones were also investigated, which afforded α-branched steric hindrance products. A potential application of α-alkylation of methylene acetone to synthesize donepezil was demonstrated, which provided the desired product in 83% yield. Finally, this catalytic system could be applied to a one-pot double alkylation procedure with sequential addition of two different alcohols. The current protocol is featured with several characteristics, including a broad substrate scope, low catalyst (0.50 mol %) loadings, and environmental benignity.
- Cao, Xiao-Niu,Wan, Xiao-Min,Yang, Fa-Liu,Li, Ke,Hao, Xin-Qi,Shao, Tian,Zhu, Xinju,Song, Mao-Ping
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p. 3657 - 3668
(2018/04/14)
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- Acceptorless dehydrogenation and dehydrogenative coupling of alcohols catalysed by protic NHC ruthenium complexes
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A new family of protic NHC Ru complexes ligated with a phosphine-tethered imidazole moiety were prepared, which can act as excellent catalysts for acceptorless dehydrogenation of secondary alcohols and dehydrogenative coupling of primary and secondary alcohols, thus leading to the formation of a variety of carbonyl compounds with release of H2.
- Chang, Weihong,Gong, Xue,Wang, Shuizhong,Xiao, Ling-Ping,Song, Guoyong
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supporting information
p. 3466 - 3471
(2017/04/26)
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- Use of a Cyclometalated Iridium(III) Complex Containing a N∧C∧N-Coordinating Terdentate Ligand as a Catalyst for the α-Alkylation of Ketones and N-Alkylation of Amines with Alcohols
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A cyclometalated iridium(III) complex containing a N∧C∧N-coordinating terdentate ligand [Ir(dpyx-N,C,N)Cl(μ-Cl)]2 was found to be a general and highly effective catalyst for the α-alkylation of ketones and N-alkylation of amines with alcohols. In the presence of catalyst (1 mol % Ir) and base (0.2-0.5 equiv), a variety of desirable products were obtained in good yields under an air atmosphere. Notably, this research exhibited the new potential of Ir(III) complexes bearing non-Cp? ligand and will facilitate the progress of the hydrogen autotransfer process.
- Liu, Pengcheng,Liang, Ran,Lu, Lei,Yu, Zhentao,Li, Feng
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p. 1943 - 1950
(2017/02/26)
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- Method for synthesizing alpha-alkyl ketone under catalysis of iridium
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The invention discloses a method for synthesizing alpha-alkyl ketone under catalysis of iridium. The method comprises steps as follows: ketone, an alcohol compound, a iridium complex catalyst, alkali and a solvent, namely, tert-amyl alcohol are added to a reaction container, the reaction mixture is subjected to a reflux reaction in the air and cooled to the room temperature after the reaction ends, a solvent is removed through rotary evaporation, and a target compound is obtained through column separation. A tridentate iridium complex with an N^C^N ligand is used, all that is required is to add 0.2 equivalents of carbonate during the reaction in the air, the reaction takes only 10-12 h, and remarkable advantages are shown. Therefore, the reaction meets the green chemistry requirement, and broad development prospect is realized.
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Paragraph 0085; 0086; 0087; 0088; 0089
(2017/07/12)
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- Hydrogen autotransfer and related dehydrogenative coupling reactions using a rhenium(i) pincer catalyst
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A novel rhenium complex bearing a non-innocent PNP pincer ligand was prepared. This novel catalyst is active in hydrogen autotransfer reactions to form new C-C and C-N bonds. More specifically, valuable alkylations of ketones and sulfonamides with primary alcohols are herein presented. In addition, the first examples of rhenium-catalysed synthesis of pyrroles are described by dehydrogenative coupling of diols, amines and ketones.
- Piehl, Patrick,Pe?a-López, Miguel,Frey, Anna,Neumann, Helfried,Beller, Matthias
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supporting information
p. 3265 - 3268
(2017/03/20)
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- Efficient alkylation of ketones with primary alcohols catalyzed by ruthenium(II)/P,N ligand complexes
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An efficient catalytic system containing [RuCl2(η6-p-cymene)]2 and one P,N ligand, N-diphenylphosphino-2-aminopyridine (L1) was loaded in catalyzing the alkylation of ketones with primary alcohols for a diverse array of substrates. Other five P,N ligands based on pyridin-2-amine and pyrimidin-2-amine were also examined in this reaction to explore the influence of steric hindrance and electronic effects. Monitoring by 1H NMR and ESI-MS reveals a stable cationic L1-coordinated ruthenium hydride intermediate, identified as [Ru(η6-p-cymene)(κ2-L1)H]+. Organic intermediates consistent with a three-step dehydrogenation, alkylation and hydrogenation pathway were also observed. The final step in this reaction, the ruthenium-catalysed transfer hydrogenation reduction of α,β-unsaturated ketone with benzyl alcohol was performed separately.
- Liu, Shi-Yuan,Xu, Lin-Yan,Liu, Chun-Yu,Ren, Zhi-Gang,Young, David James,Lang, Jian-Ping
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p. 2374 - 2381
(2017/04/03)
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- Manganese-Catalyzed Hydrogen-Autotransfer C?C Bond Formation: α-Alkylation of Ketones with Primary Alcohols
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A novel catalytic hydrogen-autotransfer protocol for the atom-efficient α-alkylation of ketones with readily available alcohols is presented. The use of manganese complexes bearing non-innocent PNP pincer ligands enabled the functionalization of a broad range of valuable ketones, including 2-oxindole, estrone 3-methyl ether, and testosterone. Mechanistic investigations suggest the participation of an intramolecular amidate-assisted alcohol-dehydrogenation process.
- Pe?a-López, Miguel,Piehl, Patrick,Elangovan, Saravanakumar,Neumann, Helfried,Beller, Matthias
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supporting information
p. 14967 - 14971
(2016/11/25)
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- Palladium- meta -terarylphosphine catalyst for the Mizoroki-Heck reaction of (hetero)aryl bromides and functional olefins
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The evolutionary meta-terarylphosphine ligand architecture of Cy?Phine was recently shown to be a key feature that imposed outstanding performance in palladium-catalyzed copper-free Sonogashira applications. Herein, the Pd-Cy?Phine combination has similar
- Tay, Daniel Weiliang,Jong, Howard,Lim, Yee Hwee,Wu, Wenqin,Chew, Xinying,Robins, Edward G.,Johannes, Charles W.
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p. 4054 - 4063
(2015/05/05)
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- Iridium-CNP complex catalyzed cross-coupling of primary alcohols and secondary alcohols by a borrowing hydrogen strategy
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A highly efficient C-C bond formation has been developed through the cross-coupling of primary and secondary alcohols. The corresponding functionalized ketones were obtained with an iridium-CNP complex as a catalyst through the borrowing hydrogen strategy. The present methodology provides an easy alternative method to aldol reaction derivatives. More importantly, the complexes were also effective catalysts for the alkylation of an aromatic amine with a tertiary alkyl amine. This journal is
- Wang, Dawei,Zhao, Keyan,Yu, Xin,Miao, Hongyan,Ding, Yuqiang
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p. 42924 - 42929
(2015/02/19)
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- An efficient ligand free chemoselective transfer hydrogenation of olefinic bonds by palladium nanoparticles in an aqueous reaction medium
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A highly efficient ligand free catalytic system was developed for chemoselective transfer hydrogenation of α,β-unsaturated carbonyl compounds by palladium nanoparticles (PdNPs) in an aqueous reaction medium. The developed methodology offers chemoselective 1,4-reduction of various α,β-unsaturated carbonyl compounds such as carbonyls, amides, esters and nitriles with excellent chemoselectivity and effective catalyst recyclability. This journal is the Partner Organisations 2014.
- Bagal, Dattatraya B.,Bhanage, Bhalchandra M.
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p. 32834 - 32839
(2014/08/18)
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- Chemoselective transfer hydrogenation of α,β-unsaturated carbonyls using palladium immobilized ionic liquid catalyst
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This work reports a simple and highly efficient protocol for chemoselective transfer hydrogenation of α,β-unsaturated carbonyls using immobilized palladium metal-containing ionic liquid as a versatile heterogeneous catalyst with an excellent conversion and chemoselectivity (up to 100 %). The influence of various reaction parameters such as the effect of hydrogen donor, solvent, temperature, and time were studied. The catalyst was recycled for four consecutive cycles without significant loss in the catalytic activity. The developed protocol is more advantageous due to the use of HCOONH4 as a hydrogen source, mild reaction conditions, and simple workup procedure and applicable for a wide range of substrates.
- Patil, Nilesh M.,Sasaki, Takehiko,Bhanage, Bhalchandra M.
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p. 1803 - 1809
(2015/02/19)
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- Direct α-alkylation of ketones with primary alcohols catalyzed by iridium-CNP complex
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The α-alkylation of ketones with primary alcohols was realized by CC cross-coupling with iridium-CNP complexes as catalyst. This reaction proceeds via dehydrogenation reactions, aldol condensation, and hydrogenation using the borrowed hydrogen atoms from alcohols. The pyridyl methanols and other heterocyclic substituted methanols, especially alkyl alcohols, were also suitable for this transformation.
- Wang, Dawei,Zhao, Keyan,Ma, Piming,Xu, Chongying,Ding, Yuqiang
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supporting information
p. 7233 - 7235
(2015/01/09)
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- Aldehyde-catalyzed transition metal-free dehydrative β-alkylation of methyl carbinols with alcohols
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Different to the borrowing hydrogen strategy in which alcohols were activated by transition metal-catalyzed anaerobic dehydrogenation, the direct addition of aldehydes was found to be an effective but simpler way of alcohol activation that can lead to efficient and green aldehyde-catalyzed transition metal-free dehydrative C-alkylation of methyl carbinols with alcohols. Mechanistic studies revealed that the reaction proceeds via in situ formation of ketones by Oppenauer oxidation of the methyl carbinols by external aldehydes, aldol condensation, and Meerwein-Ponndorf-Verley (MPV)-type reduction of α,β-unsatutated ketones by substrate alcohols, affording the useful long chain alcohols and generating aldehydes and ketones as the by-products that will be recovered in the next condensation to finish the catalytic cycle. Copyright
- Xu, Qing,Chen, Jianhui,Liu, Quan
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supporting information
p. 697 - 704
(2013/04/10)
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- RuHCl(CO)(PPh3)3-catalyzed R-alkylation of ketones with primary alcohols
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The α-alkylation reaction of ketones with primary alcohols to give α-alkylated ketones was achieved using RuHCl(CO)(PPh3) 3 as a catalyst in the presence of Cs2CO3 as a base. This reaction proceeds via an aldol condensation of ketones with aldehydes, formed via transfer dehydrogenation of alcohols, to give α,β-unsaturated ketones, which then undergo transfer hydrogenation with primary alcohols to give R-alkylated ketones and aldehydes, the latter of which participate in the next catalytic cycle. While the reaction of aliphatic primary alcohols was sluggish compared with that of benzylic alcohols, a catalytic amount of 1,10-phenanthroline was found to promote the alkylation dramatically.
- Kuwahara, Takashi,Fukuyama, Takahide,Ryu, Ilhyong
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supporting information
p. 4703 - 4705,3
(2020/09/16)
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- Cross-coupling reaction of alcohols for carbon-carbon bond formation using pincer-type NHC/palladium catalysts
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A cross-coupling reaction of different alcohols was achieved using a pincer-type NHC/PdBr complex as the catalyst precursor, and the reaction, under either Ar or H2 gas, displayed a broad substrate scope with respect to both primary and secondary alcohol components, with high alcohol product selectivity. The Royal Society of Chemistry 2010.
- Kose, Osamu,Saito, Susumu
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supporting information; experimental part
p. 896 - 900
(2010/06/20)
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- Branch-selective intermolecular hydroacylation: Hydrogen-mediated coupling of anhydrides to styrenes and activated olefins
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(Chemical Equation Presented) Branching out with hydrogen: Hydrogenation of symmetric or mixed carboxylic anhydrides in the presence of styrenes or activated olefins generates intermolecular hydroacylation products. The use of cationic rhodium catalysts ligated by triphenylarsine (Ph3As) results in the formation of branched coupling products as single regioisomers in high yields (see scheme; cod = cycloocta-1,5-diene, ArF = 3,5-(CF 3)2C6H3).
- Hong, Young-Taek,Barchuk, Andriy,Krische, Michael J.
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p. 6885 - 6888
(2007/10/03)
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