The Experts below are selected from a list of 4482 Experts worldwide ranked by ideXlab platform
Jose R Pedro - One of the best experts on this subject based on the ideXlab platform.
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highly enantioselective aza Henry Reaction with isatin n boc ketimines
ChemInform, 2015Co-Authors: Melireth Holmquist, Gonzalo Blay, Jose R PedroAbstract:The asymmetric aza-Henry Reaction of isatin N-Boc-ketimines (I) with nitromethane in the presence of a Cu-Ph-box complex leads to a series of N-Boc-protected nitroamines (III) with high enantioselectivity in most cases.
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highly enantioselective aza Henry Reaction with isatin n boc ketimines
Chemical Communications, 2014Co-Authors: Melireth Holmquist, Gonzalo Blay, Jose R PedroAbstract:A highly enantioselective aza-Henry Reaction with isatin N-Boc ketimines using a Cu(II)–BOX complex as a catalyst is described. The Reaction, which does not require protection of the N1 atom, provides the corresponding nitroamines bearing a quaternary stereocentre with high yields and enantiomeric excesses (up to 99.9%).
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enantioselective addition of nitromethane to 2 acylpyridine n oxides expanding the generation of quaternary stereocenters with the Henry Reaction
Organic Letters, 2014Co-Authors: Melireth Holmquist, Gonzalo Blay, Carmen M Munoz, Jose R PedroAbstract:The direct asymmetric Henry Reaction with prochiral ketones, leading to tertiary nitroaldols, is an elusive Reaction so far limited to a reduced number of reactive substrates such as trifluoromethyl ketones or α-keto carbonyl compounds. Expanding the scope of this important Reaction, the direct asymmetric addition of nitromethane to 2-acylpyridine N-oxides catalyzed by a BOX-Cu(II) complex to give the corresponding pyridine-derived tertiary nitroaldols having a quaternary stereogenic center with variable yields and good enantioselectivity, is described.
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the construction of quaternary stereocenters by the Henry Reaction circumventing the usual reactivity of substituted glyoxals
Chemistry: A European Journal, 2011Co-Authors: Gonzalo Blay, Victor Hernandezolmos, Jose R PedroAbstract:The enantioselective Henry Reaction between alkyl- and arylglyoxal hydrates and nitromethane catalyzed by Cu(II)-iminopyridine complexes takes place regioselectively on the ketone carbonyl group to give chiral tertiary nitroaldols with high functional group density and enantiomeric excesses of up to 96 %. Both aromatic and aliphatic glyoxals are suitable substrates for this Reaction.
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synthesis of s sotalol and r isoproterenol via a catalytic enantioselective Henry Reaction
Tetrahedron-asymmetry, 2010Co-Authors: Gonzalo Blay, Victor Hernandezolmos, Jose R PedroAbstract:Abstract A unified approach for the synthesis of ( S )-(+)-sotalol and ( R )-(−)-isoproterenol has been developed. The enantioselective Henry Reaction of the appropriate aldehyde in the presence of a camphor-derived amino pyridine–Cu(II) complex was the key step of the synthesis. The reduction of the nitro group to give the corresponding amino alcohols followed by reductive alkylation of the amine provided the target products with high enantiomeric excesses.
Zaher M A Judeh - One of the best experts on this subject based on the ideXlab platform.
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synthesis of chiral tetrahydroisoquinoline and c2 symmetric bistetrahydroisoquinoline ligands and their application in the enantioselective Henry Reaction
Synthesis, 2016Co-Authors: Duc Thinh Khong, Zaher M A JudehAbstract:Application of chiral tetrahydroisoquinoline and bistetrahydroisoquinoline scaffolds in asymmetric Reactions is limited by the inefficient synthesis of their chiral structural variants. We have conveniently synthesized 24 such variants and applied them as ligands in the enantioselective Henry Reaction. The conformational rigidity of these ligands and the size of the coordination sphere control the enantioselectivity of the products. The conformationally rigid chiral tetrahydroisoquinoline THIQ–Cu(OAc) 2 ·H 2 O complex successfully catalyzed the enantioselective Henry Reaction between various aldehydes and nitromethane and gives the β-nitro alcohol adducts in up to 96% yield and 80% ee.
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design aspects of metal free nitrogen based catalysts and their influence on the yield in the Henry Reaction
ChemInform, 2014Co-Authors: Qiong Ji Yao, Duc Thinh Khong, Qi Gao, Zaher M A JudehAbstract:A series consisting of thirteen bisisoquinoline and bis(isoquinolin-1-yl)methane catalysts is prepared and evaluated in the metal-free Henry Reaction of (Ia).
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design aspects of metal free nitrogen based catalysts and their influence on the yield in the Henry Reaction
Synthesis, 2014Co-Authors: Qiong Ji Yao, Duc Thinh Khong, Qi Gao, Zaher M A JudehAbstract:Design aspects of metal-free nitrogen-based catalysts and their influence on the yield in the Henry Reaction are disclosed. C 1 -Symmetric, N , N -1,2-disposed amine-imine type catalysts were found to be most efficient. C 1 - N , N -1,2-Disposed 1,2,3,4-tetrahydro-1,1′-biisoquinoline selectively and efficiently catalyzed the addition of nitromethane to α-keto esters and aldehydes giving exclusively the corresponding β-nitro alcohol adducts in excellent yields under very mild conditions.
Hui Zhou - One of the best experts on this subject based on the ideXlab platform.
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asymmetric Henry Reaction of 2 acylpyridine n oxides catalyzed by a ni aminophenol sulfonamide complex an unexpected mononuclear catalyst
Molecules, 2019Co-Authors: Mouxiong Liu, Ping Deng, Dongdong Gui, Hui ZhouAbstract:The asymmetric Henry Reaction of 2-acylpyridine N-oxide remains a challenge as N-oxides generally act as competitive catalyst inhibitors or displace activating ligands. A novel variable yield (up to 99%) asymmetric Henry Reaction of 2-acypyridine N-oxides catalyzed by a Ni-aminophenol sulfonamide complex with good to excellent enantioselectivity (up to 99%) has been developed. Mechanistic studies suggest that the unique properties of the electron-pairs of N-oxides for complexation with Ni makes the unexpected mononuclear complex, rather than the previously reported dinuclear complex, the active species.
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anti selective asymmetric Henry Reaction catalyzed by a heterobimetallic cu sm aminophenol sulfonamide complex
Organic Letters, 2016Co-Authors: Ping Deng, Yan Xiong, Youmao Zeng, Hui ZhouAbstract:A novel heterobimetallic Cu/Sm/aminophenol sulfonamide complex has been developed by a convenient one-pot method for the anti-selective asymmetric Henry Reaction. The corresponding anti-β-nitro alcohols are obtained in up to 99% yield, >30:1 dr, and 98% ee. The results of control experiments and ESI-MS analysis of the complex indicate that the monomeric bimetallic Cu/Sm/1 complex would be the active species.
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asymmetric Henry Reaction catalyzed by a chiral dinuclear nickel complex
Synlett, 2014Co-Authors: Yajun Liu, Ping Deng, Yan Xiong, Hui ZhouAbstract:Several chiral polyfunctional ligands were conveniently synthesized from l -amino acids and used to prepare the dinuclear complex in situ. A novel bimetallic catalyst containing dinuclear nickel was developed and applied to the asymmetric Henry Reaction. With the assistance of N-methylmorpholine, good enantioselectivities (up to 91% ee) and moderate yields (up to 72%) were obtained for aryl, heteroaryl, and aliphatic aldehydes. The pathway was air tolerant and easily manipulated, and the reagents were readily available.
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highly enantioselective aza Henry Reaction of n tosyl imines catalyzed by n n dioxide cu i complexes
ChemInform, 2008Co-Authors: Hui Zhou, Xiaohua Liu, Dan Peng, Bo Qin, Zongrui Hou, Xiaoming FengAbstract:The N,N'-dioxide-Cu(I) complexes have been developed to catalyze the addition of nitromethane to N-tosyl aldimines. The aza-Henry Reaction proceeds smoothly affording the corresponding nitro amines in good yields with high enantioselectivities. A catalytic cycle is proposed to explain the origin of reactivity.
Man Zhang - One of the best experts on this subject based on the ideXlab platform.
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the first 4 4 imidazolium tagged c2 symmetric bis oxazolines application in the asymmetric Henry Reaction
ChemInform, 2015Co-Authors: Liwei Tang, Xiao Dong, Zhiming Zhou, Yingqiang Liu, Li Dai, Man ZhangAbstract:The title compounds, synthesized from dimethylmalonic acid, are successfully used as chiral ligands in the copper(II)-catalyzed asymmetric Henry Reaction of various aromatic aldehydes (I) and nitromethane (II).
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the first 4 4 imidazolium tagged c2 symmetric bis oxazolines application in the asymmetric Henry Reaction
RSC Advances, 2015Co-Authors: Liwei Tang, Xiao Dong, Zhiming Zhou, Yingqiang Liu, Li Dai, Man ZhangAbstract:Highly efficient and recyclable imidazolium-tagged bis(oxazolines), with an imidazolium tagged onto the 4,4′-position of the box, have been designed and prepared for the first time. They have been synthesized from dimethylmalonic acid and used as chiral ligands in the copper(II)-catalyzed classic asymmetric Henry Reaction between aldehydes and nitromethane. A systematic analysis of the anions showed that the best ligand was one of a medium size; the catalyst achieved a high activity and enantioselectivity as well as good recyclability, i.e., product (R)-11k was attained at 94% ee in MeOH. Moreover, the catalyst was successfully recycled six times, without an obvious loss in activity or enantioselectivity. Finally, a theoretical mechanistic study was conducted to explain the origin of the enantioselectivity and how the size of anions affects the Reaction.
Sukwon Hong - One of the best experts on this subject based on the ideXlab platform.
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development of bifunctional aza bis oxazoline copper catalysts for enantioselective Henry Reaction
ChemInform, 2011Co-Authors: Kai Lang, Jongwoo Park, Sukwon HongAbstract:The new Cu complexes, generated from CUC and the bis(oxazolines) (Ia) and (Ib) highly efficient catalysts for the asymmetric Henry Reaction.
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development of bifunctional aza bis oxazoline copper catalysts for enantioselective Henry Reaction
Journal of Organic Chemistry, 2010Co-Authors: Kai Lang, Jongwoo Park, Sukwon HongAbstract:Base-functionalized aza-bis(oxazoline) ligands were prepared to explore the concept of dual activation through the Lewis acid and a tethered tertiary amine base. The catalytic activity of the Cu complex was evaluated for the asymmetric Henry Reaction. Compared with a corresponding unfunctionalized copper complex with external 1-benzyl-4-ethylpiperazine base, the ethylpiperazine-functionalized aza-bis(oxazoline) copper catalyst resulted in rate acceleration (2.5 times) as well as improved enantioselectivity (72% ee vs 92% ee).