- Novel use of cross-linked poly(N-isopropylacrylamide) gel for organic reactions in aqueous media
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A poly(N-isopropylacrylamide) (PNIPAAm) gel cross-linked with quaternized aminoalkyls was designed. A novel recyclable system based on the external solvent-responsive oil-absorption/elution transition ability of the PNIPAAm gel matrix was then developed.
- Hamamoto, Hiromi,Kudoh, Masahiro,Takahashi, Hideyo,Ikegami, Shiro
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Read Online
- Palladium diaqua and hydroxo complexes with polymer-supported BINAP ligands and their use for catalytic enantioselective reactions
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We report the preparation of palladium complexes with the polymer-supported BINAP ligands, [Pd(PS-(R)-binap)(H2O)2]2+(BF4-)2 (5) and [{Pd(PS-(R)-binap)(μ-OH)}2]2+(BFs
- Fujii, Akio,Sodeoka, Mikiko
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Read Online
- Selective Cα-O Bond Cleavage of α,β-Epoxy Ketones to Aldols induced by Free Radical Processes
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Several α,β-epoxy ketones were converted to aldols in good yields upon irradiation or heating with azoisobutyronitrile in the presence of tributyltin hydride in benzene; the reactions involve selective Cα-O bond cleavage of the oxiranylmethyl r
- Hasegawa, Eietsu,Ishiyama, Kenyuki,Horaguchi, Takaaki,Shimizu, Takahachi
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Read Online
- Chiral Bipyridine Ligand with Flexible Molecular Recognition Site: Development and Application to Copper-Catalyzed Asymmetric Borylation of α,β-Unsaturated Ketones
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A novel chiral bipyridine ligand bearing a flexible side chain with a molecular recognition site enables precise stereocontrol through the cooperative action of metal center and hydrogen bonds. This new chiral ligand was applied to the copper-catalyzed as
- Tsutsumi, Ryosuke,Taguchi, Rika,Yamanaka, Masahiro
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- Cellulosic CuI Nanoparticles as a Heterogeneous, Recyclable Catalyst for the Borylation of α,β-Unsaturated Acceptors in Aqueous Media
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Abstract: We have demonstrated that cellulosic CuI nanoparticles could perform as an efficient heterogeneous catalyst for the synthesis of useful organoboron compounds. Desired β-borylation products were all obtained in good to excellent yields under mild
- Zhou, Lijie,Han, Biao,Zhang, Yaoyao,Li, Bojie,Wang, Liansheng,Wang, Jianying,Wang, Xianbao,Zhu, Lei
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p. 3220 - 3229
(2021/03/06)
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- Synthesis method of alpha or beta-substituted aromatic ketone
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The invention discloses a synthesis method of alpha-or beta-substituted aromatic ketone. The method comprises the following steps: under the condition of inert gas, reacting alpha-oxo-aryl ethanone compounds, B2pin2, PDI-CoCl2 and MBHEt3 in an organic solvent at room temperature, then adding a compound 2, and continuously reacting to obtain a compound 3, wherein in the MBHEt3, M is an alkali metal; the compound 2 is selected from the group consisting of deuterated methanol, Selectfluoro, a TogniII reagent or R2CHO; R2 is an aromatic substituent or alkyl; the organic solvent is an aprotic organic solvent. According to the method, the alpha-oxo aryl ethanone is used as a raw material, a cheap and stable boron reagent and an efficient cobalt catalyst which is cheap and easy to obtain are used, an activating reagent MBHEt3 is added to generate an enol boron ether intermediate, then the enol boron ether intermediate and different electrophilic reagents are synthesized into alpha-or beta-substituted aromatic ketone, the reaction is carried out at normal temperature, and the operation is convenient.
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Paragraph 0022-0035
(2021/05/01)
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- All at once arrangement of both oxygen atoms of dioxygen into aliphatic C(sp3)-C(sp3) bonds for hydroxyketone difunctionalization
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Both β- and γ- hydroxyketone structures are important units in biologically active molecules, synthetic drugs and fine chemicals. Although there are some routes available for their manufacture from pre-functionalized groups on one or two matrix molecule(s), the approaches to simply and simultaneously deposit two oxygen atoms from dioxygen into two specific C(sp3) positions of pure saturated hydrocarbons have rarely succeeded because they are involved in the targeted activation of three inert C-H σ bonds all at once. Here, we show that a TiO2-CH3CN photocatalytic suspension system enables the insertion of dioxygen into one C(sp3)-C(sp3) bond of strained cycloparaffin derivatives, by which difunctionalized hydroxyketone products are obtained in a one-pot reaction. With the cleavage event to release strain as the directional driving force, as-designed photocatalytic reaction systems show 21 examples of β-hydroxyketone products with 31%–76% isolated yields for three-membered ring derivatives and 5 examples of γ-hydroxyketone products with 30%–63% isolated yields for four-membered ring substrates. 18O isotopic labeling experiments using 18O2, Ti18O2 and intentionally added H218O, respectively, indicated that both oxygen atoms of hydroxyketone products were exclusively from dioxygen, suggesting a previously unknown H+/TiO2-e? catalyzed arrangement pathway of the hydroperoxide intermediate to convert dioxygen into hydroxyketone units. [Figure not available: see fulltext.]
- Qiao, Xiaofeng,Lin, Yuhan,Li, Jiazhen,Ma, Wanhong,Zhao, Jincai
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p. 770 - 777
(2021/04/09)
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- Peroxide- And transition metal-free electrochemical synthesis of α,β-epoxy ketones
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A novel electrochemical method for the synthesis of α,β-epoxy ketones is reported. With KI as the redox mediator, methyl ketones reacted with aldehydes under peroxide- and transition metal-free electrolytic conditions and afforded α,β-epoxy ketones in one pot (36 examples, 52-90% yield). This safe and environmental-friendly method has a broad substrate scope and can readily provide a variety of α,β-epoxy ketones in gram-scales for evaluation of their anti-cancer activities.
- Zhang, Mengxun,Chen, Tie,Fang, Shisong,Wu, Weihua,Wang, Xin,Wu, Haiqiang,Xiong, Yongai,Song, Jun,Li, Chenyang,He, Zhendan,Lee, Chi-Sing
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supporting information
p. 2481 - 2486
(2021/04/02)
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- Diastereo- and Enantioselective Catalytic Radical Oxysulfonylation of Alkenes in β,γ-Unsaturated Ketoximes
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The asymmetric radical-initiated difunctionalization of internal alkenes, which creates two vicinal stereocenters, has been a significant synthetic challenge despite the tremendous progress achieved for terminal alkenes. This is attributable to the common
- Cheng, Gui-Juan,Gu, Qiang-Shuai,Li, Xi-Tao,Li, Zhong-Liang,Liu, Xin-Yuan,Lv, Ling,Wang, Ting,Xu, Guo-Xing,Ye, Liu,Zhang, Xinhao
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supporting information
p. 1692 - 1706
(2020/07/08)
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- 1,3 - Diphenyl -1 - propanol and preparation method thereof
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The invention relates to 1, 3-diphenyl-1-propanol and a preparation method thereof and belongs to the technical field of chemical synthesis. The preparation method comprises that benzaldehyde and acetophenone undergo a catalytic reaction in the presence of dibenzylamine trifluoroacetate and a catalyst to produce 3-hydroxy-1, 3-diphenyl-1-propanone, and the 3-hydroxy-1, 3-diphenyl-1-propanone undergoes a Huang Minglon reduction reaction to produce 1, 3-diphenyl-1-propanol, wherein the catalyst is L-proline or D-proline. The preparation method has simple processes, realizes a low cost and prepares an optically pure product satisfying the requirements. The invention also relates to 1, 3-diphenyl-1-propanol obtained by the preparation method.
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Paragraph 0063; 0072-0074
(2020/11/11)
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- Basic Anion-Exchange Resin-Catalyzed Aldol Condensation of Aromatic Ketones with Aldehydes in Continuous Flow
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A general method for the aldol condensation of aromatic ketones with aldehydes was developed under continuous-flow conditions using a commercially available, strongly basic anion-exchange resin (A26) as catalyst. This procedure, in addition to exhibiting a wide substrate scope, promoted carbon-carbon bond formation under mild conditions using a quasi-stoichiometric ratio of starting reagents with good to excellent yields, thereby forming a limited amount of waste and allowing the process to be applied to sequential-flow systems. A proof of concept was developed in the first fully heterogeneously catalyzed two-step flow synthesis of donepezil, which is a blockbuster commercial anti-Alzheimer's drug.
- Laroche, Benjamin,Saito, Yuki,Ishitani, Haruro,Kobayashi, Shū
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supporting information
p. 961 - 967
(2019/05/02)
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- Preparation and characterization of magnetic graphene nanocomposite containing Cu(proline)2 as catalyst for asymmetric aldol reactions
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A new catalyst has been prepared via immobilization of Cu(proline)2 complex onto the surface of magnetic graphene. The fabricated nanocatalyst was characterized by Fourier-transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD) analysis, vibrating-sample magnetometry (VSM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), inductively coupled plasma (ICP) techniques, and elemental analysis. Its catalytic performance was investigated in the aldol reaction using a mild and ecofriendly procedure. The synthesized nanocomposite, which contains Cu(II) center as Lewis acid, was found to be an efficient catalyst for asymmetric aldol reactions, affording corresponding aldol products in high yield and excellent enantiomeric excess (> 90?%). The examined catalyst was prepared from low-cost, easily available starting materials and can be readily isolated by magnetic decantation for recycling and reuse in consecutive reactions without significant loss of activity.
- Kooti,Kooshki,Nasiri
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p. 2641 - 2656
(2019/02/14)
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- Visible-Light-Mediated Aerobic Oxidation of Organoboron Compounds Using in Situ Generated Hydrogen Peroxide
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A simple and general visible-light-mediated oxidation of organoboron compounds has been developed with rose bengal as the photocatalyst, substoichiometric Et3N as the electron donor, as well as air as the oxidant. This mild and metal-free protocol shows a broad substrate scope and provides a wide range of aliphatic alcohols and phenols in moderate to excellent yields. Notably, the robustness of this method is demonstrated on the stereospecific aerobic oxidation of organoboron compounds.
- Weng, Wei-Zhi,Liang, Hao,Zhang, Bo
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supporting information
p. 4979 - 4983
(2018/08/24)
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- Kinetic Resolution of β-Hydroxy Carbonyl Compounds via Enantioselective Dehydration Using a Cation-Binding Catalyst: Facile Access to Enantiopure Chiral Aldols
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A practical and highly enantioselective nonenzymatic kinetic resolution of racemic β-hydroxy carbonyl (aldol) compounds through enantioselective dehydration process was developed using a cation-binding Song's oligoethylene glycol (oligoEG) catalyst with p
- Paladhi, Sushovan,Hwang, In-Soo,Yoo, Eun Jeong,Ryu, Do Hyun,Song, Choong Eui
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supporting information
p. 2003 - 2006
(2018/04/16)
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- Cascade Reaction by Chemo- and Biocatalytic Approaches to Obtain Chiral Hydroxy Ketones and anti 1,3-Diols
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A chemo- and biocatalytic cascade approach was applied for the stereoselective synthesis of hydroxy ketones and the corresponding 1,3-diols. A new class of tridentate N,N,O ligands was used with copper(II) complexes for the asymmetric β-borylation of α,β-unsaturated compounds. The complex containing ligand L5 emerged as the best performer, and it gave the organoborane derivatives with good ee values. The corresponding keto–alcohol compounds were then bioreduced by yeasts. The biotransformation set up with Rhodotorula rubra allowed (R)-keto–alcohols and (S,S)-diols to be obtained with up to 99 % ee and up to 99 % de in favor of the anti enantiomers.
- Gandolfi, Raffaella,Facchetti, Giorgio,Christodoulou, Michael S.,Fusè, Marco,Meneghetti, Fiorella,Rimoldi, Isabella
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p. 393 - 400
(2018/06/04)
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- Method for preparing organoboron compound and beta-hydroxy compound by supported copper ion Y type molecular sieve catalyst
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The invention relates to a method for preparing an organoboron compound and a beta-hydroxy compound by a supported copper ion Y type molecular sieve catalyst. The method for preparing the organoboroncompound mainly comprises the following steps: the step
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- Basic Copper Carbonate-Catalyzed Silyl Conjugate Additions to α,β-Unsaturated Carbonyls in Water
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We report here the silylation of α,β-unsaturated acceptors in water at room temperature using a copper catalyst. A broad substrate scope, including chalcone derivatives, esters, nitrile, and dienones, has been explored. In all cases, the reaction proceede
- Wang, Wei,Li, Bo-Jie,Xiao, Zu-Feng,Yan, Feng,Wei, Peng-Ren,Wang, Lian-Sheng,Zhu, Lei
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- Methods of preparing organic boron compound and beta-carbonyl compound by catalyzing copper ion loaded chitosan microspheres
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The invention relates to methods of preparing an organic boron compound and a beta-carbonyl compound by catalyzing copper ion loaded chitosan microspheres. The preparation method of the organic boroncompound mainly comprises the following steps of A, addi
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Paragraph 0077-0083
(2018/03/09)
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- Β - hydroxy ketone compounds
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The invention provides a synthesis method for a beta-hydroxy-ketone compound shown in a formula (III). The method comprises the steps that substitute vinyl acetate shown in a formula (I), a substitute alcohol compound shown in a formula (II) and an oxidizing agent are mixed to obtain reaction liquid, and the reaction liquid reacts for 2-12 hours at the temperature of 20 DEG C-120 DEG C, and then is treated to obtain the beta-hydroxy-ketone compound. The method is safe and environmentally friendly, and is a new path for synthesizing the beta-hydroxy-ketone compound containing various substituents, the substrate adaptability is good, and the reaction operation is easy.
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Paragraph 0065-0067
(2017/08/25)
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- Method used for preparing organic silicon compounds and beta-hydroxyl compounds via bivalent copper ion catalysis
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The invention relates to a method used for preparing organic silicon compounds and beta-hydroxyl compounds via bivalent copper ion catalysis. According to the method, a bivalent copper salt is taken as a catalyst, a pyridyl compound is taken as a ligand, bis(pinacolato)diboron dimethylsilane reagent is taken as a silicon reagent, and pure water is taken as a solvent; silicone additive reaction of alpha, beta-unsaturated carbonyl compounds with different substituent groups is carried out so as to obtain the organic silicon compounds; potassium bromide and peracetic acid are added directly without separation and purification of the organic silicon compounds, and the beta-hydroxyl compounds are obtained via oxidation. The advantages of the method are that: the method is simple and convenient; the raw materials are widely available; cost is relatively low; popularization is convenient; catalyst using amount is low; reaction yield is high; reaction conditions are mild; pure water is taken as the solvent; reaction is carried out at room temperature; operation is simple and convenient; application range is wide; the method is suitable for silicone additive reaction of alpha, beta- unsaturated carbonyl compounds of different types; one-pot method is adopted; and production efficiency is high.
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Paragraph 0141; 0142; 0143; 0144; 0145; 0146; 0147-0150
(2017/10/07)
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- Method for preparing organoboron compound under catalytic effect of chitosan immobilized copper and application
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The invention discloses a method for preparing an organoboron compound under a catalytic effect of chitosan immobilized copper and an application. The method comprises the following steps: A) adding a chitosan immobilized copper catalyst and a ligand into a reaction tube and stirring; B) respectively continuously adding an initial raw material I and bisdiboron into a system in turn; C) stirring the whole reaction system and reacting under room temperature; D) after the reaction is ended, filtering the whole reaction system, washing with tetrahydrofuran, performing rotary evaporation and concentration on a filtrate, adopting a mixed solvent of ethyl acetate and petroleum ether at different ratios for performing column chromatography on the residues, separating and purifying, thereby acquiring a target product II. The silica gel is taken as a fixing phase for column chromatography. The invention also relates to the application of the prepared organoboron compound in compounding beta-hydroxy compound and anti-cancer drug molecules. The method is feasible; the operation is simple and convenient; the method is suitable for various substrates and can be used for successfully preparing the corresponding target compounds. The catalyst is low in dosage and is recyclable, is easily separated after the ending of the reaction, is free from metal residue and is suitable for large-scale production.
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- Double Catalytic Kinetic Resolution (DoCKR) of Acyclic anti-1,3-Diols: The Additive Horeau Amplification
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The concept of a synergistic double catalytic kinetic resolution (DoCKR) as described in this article was successfully applied to racemic acyclic anti-1,3-diols, a common motif in natural products. This process takes advantage of an additive Horeau amplif
- Merad, Jérémy,Borkar, Prashant,Caijo, Frédéric,Pons, Jean-Marc,Parrain, Jean-Luc,Chuzel, Olivier,Bressy, Cyril
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supporting information
p. 16052 - 16056
(2017/11/21)
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- Asymmetric chemoenzymatic synthesis of 1,3-diols and 2,4-disubstituted aryloxetanes by using whole cell biocatalysts
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Regio- and stereo-selective reduction of substituted 1,3-aryldiketones, investigated in the presence of different whole cell microorganisms, was found to afford β-hydroxyketones or 1,3-diols in very good yields (up to 95%) and enantiomeric excesses (up to 96%). The enantiomerically enriched aldols, obtained with the opposite stereo-preference by baker's yeast and Lactobacillus reuteri DSM 20016 bioreduction, could then be diastereoselectively transformed into optically active syn- or anti-1,3-diols by a careful choice of the chemical reducing agent (diastereomeric ratio up to 98 : 2). The latter, in turn, were stereospecifically cyclized into the corresponding oxetanes in 43-98% yields and in up to 94% ee, thereby giving a diverse selection of stereo-defined 2,4-disubstituted aryloxetanes.
- Vitale, Paola,Perna, Filippo Maria,Agrimi, Gennaro,Scilimati, Antonio,Salomone, Antonio,Cardellicchio, Cosimo,Capriati, Vito
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supporting information
p. 11438 - 11445
(2016/12/16)
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- Direct asymmetric aldol reaction of acetophenones with aromatic aldehydes catalyzed by chiral Al/Zn heterobimetallic compounds
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Chiral Al/Zn heterobimetallic complexes are effective catalysts for the direct highly enantioselective aldol reaction of acetophenones with aromatic aldehydes. The Al site in the complex acts as a Lewis acid to activate aldehyde, whereas ethylzinc alkoxide plays a role of a Br?nsted base to form a reactive zinc enolate with acetophenone. Distinct nature of two different metals contributes to the efficient direct asymmetric aldol reaction.
- Li, Xiao,Zhang, Lei,Xiao, Yu-Hua,Guo, Qi-Peng,Da, Chao-Shan,Li, Hong,Liu, Xiaoju,Ma, Xiangrong,Ma, Yajun
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p. 1922 - 1930
(2016/10/04)
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- Highly selective multifunctional nanohybrid catalysts for the one-pot synthesis of α,β-epoxy-chalcones
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An efficient one-pot heterogeneous process for producing chiral α,β-epoxy-chalcones from the corresponding aldehydes and ketones has been described. The nanohybrid materials based on poly-l-leucine immobilised into rehydrated hydrotalcites did not require any pre-activation and were easily recovered and recycled for four consecutive runs without losing their catalytic efficiency in terms of conversion, total selectivity towards the corresponding epoxy-chalcones and excellent enantioselectivity.
- Crivoi, Dana-Georgiana,Segarra, Anna M.,Medina, Francesc
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p. 120 - 128
(2016/01/09)
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- A green and recyclable chitosan supported catalyst for the borylation of α,β-unsaturated acceptors in water
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We herein report a green and recyclable chitosan supported copper catalyst which is capable of catalyzing the borylation of α,β-unsaturated acceptors in water at room temperature. A broad substrate scope including chalcone derivatives, esters and nitriles have been explored. In all the cases, desired products were obtained in good to excellent yields. Remarkably, this chitosan supported catalyst could be recovered and reused for five times without any significant decrease of reactivity.
- Xu, Pengyu,Li, Bojie,Wang, Liansheng,Qin, Caiqin,Zhu, Lei
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- New artificial fluoro-cofactor of hydride transfer with novel fluorescence assay for redox biocatalysis
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A new artificial fluoro-cofactor was developed for the replacement of natural cofactors NAD(P), exhibiting a high hydride transfer ability. More importantly, we established a new and fast screening method for the evaluation of the properties of artificial cofactors based on the fluorescence assay and visible color change.
- Zhang, Lei,Yuan, Jun,Xu, Yufang,Zhang, Y.-H. Percival,Qian, Xuhong
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supporting information
p. 6471 - 6474
(2016/06/06)
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- Visible-light photoredox catalysis using a macromolecular ruthenium complex: Reactivity and recovery by size-exclusion nanofiltration in continuous flow
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A novel macromolecular photoredox catalyst based on [Ru(bpy)3]2+ anchored to a 2nd-generation PAMAM dendrimer has been developed. Its catalytic activity under visible light irradiation and recyclability using organic solvent nanofiltration with a size-exclusion membrane have been explored under continuous flow conditions.
- Guerra, Javier,Cantillo, David,Kappe, C. Oliver
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p. 4695 - 4699
(2016/07/11)
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- Pyridine salt / 1,4-dihydropyridine derivative and preparation method thereof
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The present invention discloses a pyridine salt / 1,4-dihydropyridine derivative (NAD / NADH analog) with novel structure. The NAD / NADH analog can substitute natural NAD / NADH to be applied to a biochemical system for redox reactions, and can also be used as an electron carrier for the energy transfer of an enzymatic fuel cell. Further, the NAD / NADH analogs provided by the invention are easy to prepare, isolate and purify, and have a high yield.
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Paragraph 0182; 0183; 0185; 0186; 0187
(2016/10/09)
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- Visible light-promoted reductive transformations of various organic substances by using hydroxyaryl-substituted benzimidazolines and bases
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Visible light promoted reduction reactions of organohalides, sulfonamides, organonitriles and epoxy ketones were performed using 1,3-dimethylbenzimidazolines possessing 2-hydroxynaphthyl or 2-hydroxyphenyl substituents (HOAr-DMBIH) as photo-reductants. Xe or Hg–Xe lamp through an appropriate glass-filter (λ>390 nm) and a household white light-emitting diode were used as light sources. In these reactions, reductive cleavages of carbon[sbnd]halogen, nitrogen[sbnd]sulfur, carbon[sbnd]carbon (nitrile) and carbon[sbnd]oxygen bonds take place. Bases exert significant effects on the progress of these reactions in a manner that depends on the nature of the substrate. Addition of 1,8-diazabicyclo[5.4.0]undec-7-ene as well as potassium t-butoxide significantly accelerates photo-reduction reactions of organohalides, sulfonamides and organonitriles while the decomposition of formed hydroxy ketones occurs in reactions of epoxy ketones. Single electron transfer from the photo-excited states of benzimidazolines (HOAr-DMBIH) or their deprotonated analogues (?OAr-DMBIH) to the substrates is proposed to initiate these reactions.
- Hasegawa, Eietsu,Izumiya, Norihiro,Fukuda, Takuya,Nemoto, Kazuki,Iwamoto, Hajime,Takizawa, Shin-ya,Murata, Shigeru
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p. 7805 - 7812
(2016/11/17)
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- The Complete Mechanism of an Aldol Condensation
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Although aldol condensation is one of the most important organic reactions, capable of forming new C-C bonds, its mechanism has never been fully established. We now conclude that the rate-limiting step in the base-catalyzed aldol condensation of benzaldehydes with acetophenones, to produce chalcones, is the final loss of hydroxide and formation of the C=C bond. This conclusion is based on a study of the partitioning ratios of the intermediate ketols and on the solvent kinetic isotope effects, whereby the condensations are faster in D2O than in H2O, regardless of substitution.
- Perrin, Charles L.,Chang, Kuei-Lin
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p. 5631 - 5635
(2016/07/13)
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- Conjugate Addition of Diboron Catalyzed by O -Monoacyltartaric Acids
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O-3,5-Di(adamantan-1-yl)benzoyltartaric acid catalyzes the conjugate addition of bis(neopentyl glycolato)diboron to α,β-unsaturated ketones with good enantioselectivity. The addition of magnesium sulfate as a dehydrating agent and benzoic acid as a co-cat
- Sugiura, Masaharu,Ishikawa, Wakoto,Kuboyama, Yukinobu,Nakajima, Makoto
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supporting information
p. 2265 - 2269
(2015/08/03)
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- Vanadyl species-catalyzed complementary β-oxidative carbonylation of styrene derivatives with aldehydes
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A series of oxometallic species and metal acetylacetonates (acac) was examined as catalysts for oxidative carbonylation of styrene with benzaldehyde using t-butylhydroperoxide as the co-oxidant in warm acetonitrile. Among them, VO((acac)2 and vanadyl(iv) chloride were found to be the only catalyst class to achieve cross-coupling processes by judiciously tuning the ligand electronic attributes, leading to β-hydroxylation- and β-peroxidation-carbonylation of styrene, respectively, in a complementary manner. Mechanistic studies indicated that vanadyl-associated acyl radicals generated by t-butoxy radical-assisted, homolytic cleavage of the aldehyde C-H bond were involved in tandem processes with an exclusive syn diastereoselectivity in the case of β-methylstyrene. This journal is
- Yang, Wen-Chieh,Weng, Shiue-Shien,Ramasamy, Anandhan,Rajeshwaren, Gobi,Liao, Yi-Ya,Chen, Chien-Tien
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p. 2385 - 2392
(2015/03/04)
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- A Cu(II)-based strategy for catalytic enantioselective β-borylation of α,β-unsaturated acceptors
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Cu(I)-based chemistry has flourished over the last decade because of the reliable use of species such as soft acids. However, the unique nature of Cu(ii) catalysts allows the well-documented Cu(I)-based chemistry to be extended. Prominent advantages of th
- Zhu, Lei,Kitanosono, Taku,Xu, Pengyu,Kobayashi, Shu
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p. 11685 - 11688
(2015/07/15)
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- Chiral Br?nsted Acid as a True Catalyst: Asymmetric Mukaiyama Aldol and Hosomi-Sakurai Allylation Reactions
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Highly diastereo- and enantioselective Mukaiyama aldol reaction catalyzed by a new chiral Br?nsted acid, N-(perfluorooctanesulfonyl)thiophosphoramide, is described. The perfluorooctyl substituent on the sulfonyl group of the catalyst plays an essential role in the stereoselection. The catalyst also allows the asymmetric Hosomi-Sakurai allylation, which has been considerably challenging due to the low reactivity of allylsilanes. 29Si and 31P NMR monitoring reveals the characteristic feature of the thiophosphoramide catalyst, acting as a strong Br?nsted acid even in the presence of excess silyl nucleophiles, which cannot be found in other related phosphoric acid analogues.
- Sai, Masahiro,Yamamoto, Hisashi
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p. 7091 - 7094
(2015/06/25)
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- Regio- and enantioselective reduction of diketones: Preparation of enantiomerically pure hydroxy ketones catalysed by Candida parapsilosis ATCC 7330
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Enantiomerically enriched hydroxy ketones were prepared by the reduction of the corresponding diketones with excellent enantiomeric excess (98%) and in good yields (up to 75%) using whole cells of Candida parapsilosis ATCC 7330. Cyclic diketones, such as 1,2-cyclohexanedione and 1,4-cyclohexanedione, resulted in hydroxy ketones as products. Cyclohexane-1,3-dione and 5,5-dimethylcyclohexane-1,3-dione gave dimerised products, such as 2,2′-(ethane-1,1-diyl)bis(3-hydroxycyclohex-2-enone) and 2,2′-(ethane-1,1-diyl)bis(3-hydroxy-5,5-dimethylcyclohex-2-enone) with acetaldehyde generated in situ from whole cells of Candida parapsilosis ATCC 7330, which is reported here for the first time.
- Mahajabeen, Pula,Chadha, Anju
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p. 1167 - 1173
(2015/10/28)
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- Aryl-substituted dimethylbenzimidazolines as effective reductants of photoinduced electron transfer reactions
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Photoinduced electron transfer (PET) reactions promoted by 2-aryl substituted 1,3-dimethylbenzimidazolines (Ar-DMBIH) were investigated. Excited states of Ar-DMBIH, formed by irradiation using light above 360 nm, initiate PET reductions of various organic substrates, including transformations of epoxy ketones to aldols, free radical rearrangements such as the Dowd-Beckwith ring-expansion and 5-exo hexenyl cyclization, deprotection of N-sulfonyl-indols, and allylation of acyl formates. In these processes, Ar-DMBIH possessing 1-naphthyl, 2-naphthyl, 1-pyrenyl and 9-anthryl substituents formally act as two electron and one proton donors while the hydroxynaphthyl substituted derivative serves as a two electron and two proton donor. On the basis of the results of absorption spectroscopy studies, cyclic voltammetry and DFT calculation, a mechanistic sequence for these reduction reactions is proposed that involves initial photoexcitation of the aryl chromophore of the Ar-DMBIH followed by single electron transfer (SET) to the organic substrate to generate the radical cation of benzimidazoline and the radical anion of the substrate.
- Hasegawa, Eietsu,Ohta, Taku,Tsuji, Shiori,Mori, Kazuma,Uchida, Ken,Miura, Tomoaki,Ikoma, Tadaaki,Tayama, Eiji,Iwamoto, Hajime,Takizawa, Shin-Ya,Murata, Shigeru
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p. 5494 - 5505
(2015/08/03)
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- Highly enantioselective acylation of acyclic meso 1,3-diols through synergistic isothiourea-catalyzed desymmetrization/chiroablative kinetic resolution
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A general and highly efficient organocatalyzed desymmetrization of acyclic meso 1,3-diols through acyl transfer using chiral isothioureas is described. The introduction of π-systems in the acyclic substrates provided new opportunities in terms of reactivi
- Merad, Jérémy,Borkar, Prashant,Bouyon Yenda, Tracy,Roux, Christèle,Pons, Jean-Marc,Parrain, Jean-Luc,Chuzel, Olivier,Bressy, Cyril
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supporting information
p. 2118 - 2121
(2015/05/13)
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- Strong Lewis acid air-stable cationic titanocene perfluoroalkyl(aryl) sulfonate complexes as highly efficient and recyclable catalysts for C-C bond forming reactions
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A series of strong Lewis acid air-stable titanocene perfluoroalkyl(aryl) sulfonate complexes Cp2Ti(OH2)2(OSO 2X)2·THF (X = C8F17, 1·THF; X = C4F9, 2·H2O· THF; X = C6F5, 3) were successfully synthesized by the treatment of Cp2TiCl2 with C8F 17SO3Ag, C4F9SO3Ag and C6F5SO3Ag, respectively. In contrast to well-known titanocene bis(triflate), these complexes showed no change in open air over three months. TG-DSC analysis showed that 1·THF, 2·H 2O·THF and 3 were thermally stable at 230 °C, 220°C and 280°C, respectively. Conductivity measurements showed that these complexes underwent ionic dissociation in CH3CN solution. X-ray analysis results confirmed that 2·H2O·THF and 3 were cationic. ESR spectra showed that the Lewis acidity of 1·THF (1.06 eV) was higher than that of Sc3+ (1.00 eV) and Y3+ (0.85 eV). UV/Vis spectra showed a significant red shift due to the strong complex formation between 10-methylacridone and 2·H2O·THF. Fluorescence spectra showed that the Lewis acidity of 2 (λem = 477 nm) was higher than that of Sc3+ (λem = 474 nm). These complexes showed high catalytic ability in various carbon-carbon bond forming reactions. Moreover, they show good reusability. Compared with 1·THF, 2·H2O·THF and 3 exhibit higher solubility and better catalytic activity, and will find broad applications in organic synthesis. This journal is the Partner Organisations 2014.
- Li, Ningbo,Wang, Jinying,Zhang, Xiaohong,Qiu, Renhua,Wang, Xie,Chen, Jinyang,Yin, Shuang-Feng,Xu, Xinhua
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supporting information
p. 11696 - 11708
(2014/07/22)
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- Aerobic oxidative desymmetrization of meso-diols with bifunctional amidoiridium catalysts bearing chiral N-sulfonyldiamine ligands
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Asymmetric aerobic oxidation of a range of meso- and prochiral diols with chiral bifunctional Ir catalysts is described. A high level of chiral discrimination ability of Cpa? -Ir complexes derived from (S,S)-1,2-diphenylethylenediamine was successfully demonstrated by desymmetrization of secondary benzylic diols such as cis-indan-1,3-diol and cis-1,4-diphenylbutane-1,4-diol, providing the corresponding (R)-hydroxyl ketones with excellent chemo- and enantioselectivities. Enantiotopic group discrimination in oxidation of symmetrical primary 1,4- and 1,5-diols gave rise to chiral lactones with moderate ees under similar aerobic conditions.
- Moritani, Junki,Hasegawa, Yasuharu,Kayaki, Yoshihito,Ikariya, Takao
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supporting information
p. 1188 - 1191
(2014/02/14)
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- Heterogeneous versus homogeneous copper(II) catalysis in enantioselective conjugate-addition reactions of boron in water
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We have developed CuII-catalyzed enantioselective conjugate-addition reactions of boron to α,β-unsaturated carbonyl compounds and α,β,γ,δ-unsaturated carbonyl compounds in water. In contrast to the previously reported CuI catalysis that required organic solvents, chiral CuII catalysis was found to proceed efficiently in water. Three catalyst systems have been exploited: cat. 1: Cu(OH)2 with chiral ligand L1; cat. 2: Cu(OH)2 and acetic acid with ligand L1; and cat. 3: Cu(OAc)2 with ligand L1. Whereas cat. 1 is a heterogeneous system, cat. 2 and cat. 3 are homogeneous systems. We tested 27 α,β-unsaturated carbonyl compounds and an α,β-unsaturated nitrile compound, including acyclic and cyclic α,β-unsaturated ketones, acyclic and cyclic β,β- disubstituted enones, acyclic and cyclic α,β-unsaturated esters (including their β,β-disubstituted forms), and acyclic α,β-unsaturated amides (including their β,β-disubstituted forms). We found that cat. 2 and cat. 3 showed high yields and enantioselectivities for almost all substrates. Notably, no catalysts that can tolerate all of these substrates with high yields and high enantioselectivities have been reported for the conjugate addition of boron. Heterogeneous cat. 1 also gave high yields and enantioselectivities with some substrates and also gave the highest TOF (43 200 h-1) for an asymmetric conjugate-addition reaction of boron. In addition, the catalyst systems were also applicable to the conjugate addition of boron to α,β,γ, δ-unsaturated carbonyl compounds, although such reactions have previously been very limited in the literature, even in organic solvents. 1,4-Addition products were obtained in high yields and enantioselectivities in the reactions of acyclic α,β,γ,δ-unsaturated carbonyl compounds with diboron 2 by using cat. 1, cat. 2, or cat. 3. On the other hand, in the reactions of cyclic α,β,γ,δ-unsaturated carbonyl compounds with compound 2, whereas 1,4-addition products were exclusively obtained by using cat. 2 or cat. 3, 1,6-addition products were exclusively produced by using cat. 1. Similar unique reactivities and selectivities were also shown in the reactions of cyclic trienones. Finally, the reaction mechanisms of these unique conjugate-addition reactions in water were investigated and we propose stereochemical models that are supported by X-ray crystallography and MS (ESI) analysis. Although the role of water has not been completely revealed, water is expected to be effective in the activation of a borylcopper(II) intermediate and a protonation event subsequent to the nucleophilic addition step, thereby leading to overwhelmingly high catalytic turnover. Copyright
- Kitanosono, Taku,Xu, Pengyu,Kobayashi, Shu
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supporting information
p. 179 - 188
(2014/01/06)
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- Nucleophilic gem-difluoro(phenylsulfanyl)methylation of carbonyl compounds with PhSCF2H in the presence of a phosphazene as a base
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Direct nucleophilic gem-difluoro(phenylsulfanyl)methylation of carbonyl compounds has been achieved by use of difluoro(phenylsulfanyl)methane (PhSCF2H) and the phosphazene base P4-tBu in THF. Non-enolizable aldehydes and ketones are suitable substrates to undergo nucleophilic gem-difluoro(phenylsulfanyl)methylation, providing α-gem-difluoromethylated adducts in good yields. In addition, this methodology is also applicable with cyclic imides and acid anhydrides. Direct nucleophilic gem-difluoro(phenylsulfanyl)methylation of aromatic aldehydes and ketones, cyclic imides, and acid anhydrides with difluoro(phenylsulfanyl)methane (PhSCF2H) reagent was achieved in the presence of the phosphazene P4-tBu as a base. The corresponding adducts should be useful for further synthetic conversion into a variety of fluorinated compounds. Copyright
- Punirun, Teerachai,Soorukram, Darunee,Kuhakarn, Chutima,Reutrakul, Vichai,Pohmakotr, Manat
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supporting information
p. 4162 - 4169
(2014/07/08)
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- Alkaline earth metal-based metal-organic framework: Hydrothermal synthesis, X-ray structure and heterogeneously catalyzed Claisen-Schmidt reaction
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Two alkaline earth metal-based carboxylate systems, [Mg(HL)(H 2O)2]n (1) and [Ca(H2L) 2]n (2) (H3L = chelidamic acid) have been hydrothermally synthesized, and characterized by single-crystal X-ray diffraction, IR, elemental analysis, and thermo-gravimetric analysis. Compound 1 has a 2D structure incorporating two water molecules. The dehydrated species, 1a, generated from 1 by removal of the coordinated water, has been characterized by thermo-gravimetric analysis, IR, elemental analysis and variable temperature powder X-ray diffraction. Both 1 and its dehydrated species 1a catalyze the Claisen-Schmidt reaction under heterogeneous conditions, but 1a is a more effective catalyst under environmentally friendly conditions. The catalyst can readily be recovered and reused in successive cycles without detectable loss of activity. Compound 2 has a 3D structure and is thermally stable up to 540 °C, but is inactive catalytically. This journal is the Partner Organisations 2014.
- Saha, Debraj,Maity, Tanmoy,Koner, Subratanath
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p. 13006 - 13017
(2014/08/18)
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- Synthesis and Suzuki-Miyaura cross-coupling of enantioenriched secondary potassium β-trifluoroboratoamides: Catalytic, asymmetric conjugate addition of bisboronic acid and tetrakis(dimethylamino)diboron to α,β- unsaturated carbonyl compounds
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Enantioenriched potassium β-trifluoroboratoamides have been synthesized via an asymmetric, copper-catalyzed 1,4-addition of tetrahydroxydiboron (BBA) and tetrakis(dimethylamino)-diboron to α,β-Unsaturated amides. These dibora reagents provide access to the desired organotri-fluoroborates using effective and atom economical sources of boron. The copper-catalyzed β-boration is extended to α,β- Unsaturated ketones and esters. The desired potassium organotrifluoroborates are synthesized with yields up to 92% and enantiomeric ratios up to 98:2. The enantioenriched potassium btrifluoroboratoamides are successfully cross-coupled with an array of aryl and heteroaryl chlorides in high yield with complete stereochemical fidelity as the transmetalation proceeds through an SE2 mechanism via an open transition state.
- Molander, Gary A.,Wisniewski, Steven R.,Hosseini-Sarvaria, Mona
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p. 3037 - 3057
(2014/03/21)
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- Spiro[4,4]-1,6-Nonadiene-based diphosphine oxides in lewis base catalyzed asymmetric double-aldol reactions
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Symmetry swap: A C2-chiral spiro diphosphine oxide (SpinPO) has been found to be highly efficient and enantioselective in the catalysis of double-aldol reactions of ketones and aldehydes to give the corresponding optically active double-aldol products, which can be readily transformed into optically active C3- and pseudo-C3-symmetric molecules. Copyright
- Zhang, Panke,Han, Zhaobin,Wang, Zheng,Ding, Kuiling
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supporting information
p. 11054 - 11058
(2013/10/22)
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- Effect of phosphorus amount on the particle size and catalytic performance of heterogeneous nickel(ii) schiff-base complex in aldol condensation reaction
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The organic-inorganic hybrid of citric acid, tetraethoxysilane (TEOS), and triethylphosphate (TEP) doped by a nickel Schiff-base complex was prepared by sol-gel method. The prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmittance electron microscopy (TEM), scanning tunnelling microscopy (STM), and infrared spectroscopy (IR). In order to determine the phosphorus amount effect on the catalytic activity of the prepared composites, the aldol condensation was used as a model reaction. The results revealed that the composite with 10% phosphorus is a better catalyst in comparison with other composites.
- Eshtiagh-Hosseini, Hossein,Tabari, Taymaz
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p. 1778 - 1791
(2013/11/06)
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- Synthesis and structures of air-stable binuclear hafnocene perfluorobutanesulfonate and perfluorobenzenesulfonate and their catalytic application in C-C bond-forming reactions
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The two air-stable m2-hydroxy-bridged binuclear hafnocene perfluorobutanesulfonate and perfluorobenzenesulfonate complexes were successfully synthesized. The high catalytic activity and recyclability of these complexes were exemplified for various carbon-carbon bond formation reactions. Compared with our previously reported hafnocene perfluorooctanesulfonate, these complexes show stronger Lewis acidity and better catalytic activity, and should find broad applications in organic synthesis.
- Li, Ningbo,Zhang, Xiaohong,Xu, Xinhua,Chen, Yun,Qiu, Renhua,Chen, Jinyang,Wang, Xie,Yin, Shuang-Feng
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supporting information
p. 2430 - 2440
(2013/10/01)
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- Gallium(III) triflate catalyzed diastereoselective mukaiyama aldol reaction by using low catalyst loadings
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A mild method for the diastereoselective Mukaiyama aldol reaction is reported. By using a low loading of the gallium(III) triflate catalyst (down to 0.01 mol-%), the transformation proceeds efficiently to afford the corresponding β-hydroxy ketones in yields up to 92a€‰%. To the best of our knowledge, this is the first report of a metal triflate acting as a safe, bench-stable, and slow-releasing source of triflic acid for the Mukaiyama aldol reaction. A diastereoselective Mukaiyama aldol reaction was performed under mild conditions with a low loading of the gallium(III) triflate catalyst (down to 0.01 mol-%). The transformation proceeded efficiently to afford the corresponding β-hydroxy ketones in yields up to 92a€‰%. Copyright
- Plancq, Baptiste,Justafort, Lyse Carole,Lafantaisie, Mathieu,Ollevier, Thierry
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supporting information
p. 6525 - 6529
(2013/11/06)
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- Mukaiyama aldol reaction of trimethylsilyl enolate with aldehyde catalyzed by CuI
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Cuprous iodide has been found to be a very effective catalyst for Mukaiyama aldol reaction of trimethylsilyl ketene acetal with aldehydes. The new catalytic system promotes efficiently the Mukaiyama aldol reaction in DMF to produce corresponding β-hydroxy carbonyl compounds in high yield.
- Kalita, Hima Rani,Borah, Arun Jyoti,Phukan, Prodeep
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p. 289 - 292
(2013/05/22)
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- Asymmetric β-boration of α,β-unsaturated carbonyl compounds with chiral Rh[bis(oxazolinyl)phenyl] catalysts
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Chiral rhodium[bis(oxazolinyl)phenyl] complexes exhibited high catalytic activity for the β-boration of α,β-unsaturated esters, ketones, and amides with bis(pinacolato)diboron in the presence of sodium tert-butoxide to attain high enantioselectivity of up to 97%. The substrate scope and catalytic mechanism were discussed.
- Toribatake, Kenji,Zhou, Li,Tsuruta, Ayae,Nishiyama, Hisao
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p. 3551 - 3560
(2013/05/08)
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- Production of hydroxlated flavonoids with cytochrome P450 BM3 variant F87V and their antioxidative activities
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A variant of P450 BM3 with an F87V substitution [P450 BM3 (F87V)] is a substrate-promiscuous cytochrome P450 monooxygenase. We investigated the bioconversion of various flavonoids (favanones, chalcone, and isoflavone) by using recombinant Escherichia coli cells, which expressed the gene coding for P450 BM3 (F87V), to give their corresponding hydroxylated products. Potent antioxidative activities were observed in some of the products.
- Kitamura, Emi,Otomatsu, Toshihiko,Maeda, Chiemi,Aoki, Yoko,Ota, Chihiro,Misawa, Norihiko,Shindo, Kazutoshi
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p. 1340 - 1343
(2013/07/26)
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- Biomimetic hydrogenation: A reusable NADH co-enzyme model for hydrogenation of α,β-epoxy ketones and 1,2-diketones
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A biomimetic method has been developed to transform α,β-epoxy ketones or 1,2-diketones into corresponding β-hydroxy ketones or α-hydroxy ketones using a catalytic amount of BNAH or BNA +Br-. The regeneration of BNAH or BNA+Br - is achieved by a mixture of HCOOH/Et3N. A radical mechanism is proposed to explain these observations.
- Huang, Qiang,Wu, Ji-Wei,Xu, Hua-Jian
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p. 3877 - 3881
(2013/07/05)
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