The Experts below are selected from a list of 903 Experts worldwide ranked by ideXlab platform
Tianpa You - One of the best experts on this subject based on the ideXlab platform.
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An efficient one-pot approach to phenanthrene derivatives using a catalyzed tandem Ullmann-Pinacol Coupling reaction
Tetrahedron, 2008Co-Authors: Shuang-zheng Lin, Tianpa YouAbstract:Abstract In the presence of catalyst (Ph 3 P) 2 NiCl 2 and reductant Zn, the Ullmann reactions of ortho -halo aryl aldehydes generate biaryl-dialdehydes and zinc halides. Subsequently, ZnX 2 can catalyze the intramolecular Pinacol Coupling reaction of biaryl-dialdehydes to form 9,10-dihydrophenanthrene-9,10-diols. One-pot synthesis of 9-phenanthrols can be achieved using this strategy.
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Biphenyl-oxazoline ligands derived from β-DDB: Their synthesis and application in asymmetric Pinacol Coupling reaction
Journal of Molecular Catalysis A-chemical, 2006Co-Authors: Jiwu Wen, Qitao Tan, Tianpa YouAbstract:Biphenyl-bisoxazoline ligands conveniently synthesized from β-DDB have been exploited in asymmetric Pinacol Coupling reaction for the first time. The Pinacol products were obtained with good yields, high diastereoselectivities and good enantioselectivities (up to 83%e.e.). The stereochemistry of the diol products was dominated by the steric structure of the oxazoline component. Ligands bearing bulky groups in the chiral centre of the oxazolines showed more efficient for achieving both high diastereoselectivity and enantioselectivity.
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Asymmetric Pinacol Coupling catalyzed by TADDOL-titanium complexes
Journal of Molecular Catalysis A-chemical, 2005Co-Authors: Jiwu Wen, Jun Zhao, Tianpa YouAbstract:Abstract Chiral diols 1–4 derived from tartaric acid have been exploited in asymmetry Pinacol Coupling reaction, good to excellent diastereoselectivities and moderate to good enantioselectivities were obtained.
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asymmetric Pinacol Coupling of aromatic aldehydes catalyzed by a new titanium schiff base complex
Tetrahedron-asymmetry, 2004Co-Authors: Qingshan Tian, Jun Zhao, Yan Feng, Tianpa YouAbstract:Abstract A new Schiff-base with two stereogenic centers has been prepared and its titanium complex applied to catalyze the Pinacol Coupling of aldehydes, which afforded Pinacols in high yield, excellent diastereoselectivities, and high enantioselectivities.
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Asymmetric Pinacol Coupling of aromatic aldehydes catalyzed by a new titanium–Schiff base complex
Tetrahedron: Asymmetry, 2004Co-Authors: Qing‐shan Tian, Jun Zhao, Yan Feng, Tianpa YouAbstract:Abstract A new Schiff-base with two stereogenic centers has been prepared and its titanium complex applied to catalyze the Pinacol Coupling of aldehydes, which afforded Pinacols in high yield, excellent diastereoselectivities, and high enantioselectivities.
Christophe Len - One of the best experts on this subject based on the ideXlab platform.
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Selective Pinacol-Coupling Reaction using a Continuous Flow System
The Journal of organic chemistry, 2016Co-Authors: Nicolas Sotto, Muriel Billamboz, Clément Cazorla, Carole Villette, Christophe LenAbstract:The first continuous flow Pinacol Coupling reaction of carbonyl compounds was successfully achieved within only 2 min during a single pass through a cartridge filled with zinc(0). The optimized method allowed the efficient production of gram-scale value-added compounds with high productivity. The developed methodology is efficient for aromatic or α,β-unsaturated aldehydes but gives moderate results for more stable acetophenone derivatives. Moreover, the flow method displayed better results in terms of yield and selectivity in comparison to the corresponding batch methodology.
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Selective Pinacol-Coupling Reaction using a Continuous Flow System
2016Co-Authors: Nicolas Sotto, Muriel Billamboz, Carole Villette, Clément Cazorla, Christophe LenAbstract:The first continuous flow Pinacol Coupling reaction of carbonyl compounds was successfully achieved within only 2 min during a single pass through a cartridge filled with zinc(0). The optimized method allowed the efficient production of gram-scale value-added compounds with high productivity. The developed methodology is efficient for aromatic or α,β-unsaturated aldehydes but gives moderate results for more stable acetophenone derivatives. Moreover, the flow method displayed better results in terms of yield and selectivity in comparison to the corresponding batch methodology
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Selective Pinacol Coupling on Regeneratable Supported Acids in Sole Water
The Journal of organic chemistry, 2015Co-Authors: Nicolas Sotto, Muriel Billamboz, Carole Chevrin-villette, Christophe LenAbstract:Efficient Pinacol Coupling was developed in sole water, using a reusable heterogeneous supported acid source and zinc as cheap available metal source. This medium can be easily regenerated up to 10-fold without loss of activity. Moreover, supported acids enhance the selectivity of the Pinacol Coupling reaction compared with homogeneous acids.
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simple and expeditious Pinacol Coupling of non usual α β unsaturated carbonyl compounds in water
RSC Advances, 2015Co-Authors: Muriel Billamboz, Nicolas Sotto, Christophe Len, Carole ChevrinvilletteAbstract:Using zinc (0) in a 5% v AcOH aqueous solution allowed the efficient Pinacol Coupling of aliphatic or aromatic unusual, α,β-unsaturated carbonyl compounds such as citral A in good to excellent yields (56–99%). It can also be successfully applied to acetophenone.
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First Pinacol Coupling in Emulsified Water: Key Role of Surfactant and Impact of Alternative Activation Technologies
ChemSusChem, 2015Co-Authors: Muriel Billamboz, Christophe LenAbstract:For the first time, the influence of surfactants on the radical Pinacol Coupling reaction is investigated. The rate and selectivity of this reductive C-C Coupling are compared under three different activation technologies: thermal activation, microwave irradiation, and sonication. The use of IgepalCO520, a neutral surfactant, led to the successful conversion of aromatic or α,β-unsaturated aliphatic carbonyl compounds in moderate to excellent yield (55-90 %). An insight on the potential mechanism involved in the reaction is also proposed, based on microscopic observations and particle size measurement.
Toshikazu Hirao - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Heterodinuclear Hemisalen Complexes on a Hexaarylbenzene Scaffold and Their Application for the Cross-Pinacol Coupling Reaction.
ChemInform, 2014Co-Authors: Akihiro Miyasaka, Toru Amaya, Toshikazu HiraoAbstract:Newly synthesized titanium-vanadium complexes with undefined structures are applied as catalysts in the cross-Pinacol Coupling of aliphatic and aromatic aldehydes giving a mixture of diastereomers.
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synthesis of heterodinuclear hemisalen complexes on a hexaarylbenzene scaffold and their application for the cross Pinacol Coupling reaction
Chemistry: A European Journal, 2014Co-Authors: Akihiro Miyasaka, Toru Amaya, Toshikazu HiraoAbstract:Intermolecular cross-Pinacol Coupling reaction between aliphatic and aromatic aldehydes by using heterodinuclear hemisalen complexes 1cis with vanadium(V) and titanium(IV) on a hexaarylbenzene scaffold is reported. Our ligand design is based on the individual activation of two aldehydes by vanadium and titanium, which are positioned with a suitable space on the rigid scaffold. Ligands such as 1cis were synthesized by Diels-Alder addition and decarbonylation reaction, followed by condensation of dialdehyde 3cis with various aminophenols. The influence of the substituents on the ligands on the Pinacol Coupling reaction was investigated. As a result, the reductive Coupling reaction between aliphatic and aromatic aldehydes by using a catalytic amount of 1cis in the presence of Me3 SiCl and Zn provided the corresponding cross-coupled 1,2-diol in good yields with high cross-selectivity.
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Synthesis of Heterodinuclear Hemisalen Complexes on a Hexaarylbenzene Scaffold and their Application for the Cross‐Pinacol Coupling Reaction
Chemistry (Weinheim an der Bergstrasse Germany), 2014Co-Authors: Akihiro Miyasaka, Toru Amaya, Toshikazu HiraoAbstract:Intermolecular cross-Pinacol Coupling reaction between aliphatic and aromatic aldehydes by using heterodinuclear hemisalen complexes 1cis with vanadium(V) and titanium(IV) on a hexaarylbenzene scaffold is reported. Our ligand design is based on the individual activation of two aldehydes by vanadium and titanium, which are positioned with a suitable space on the rigid scaffold. Ligands such as 1cis were synthesized by Diels-Alder addition and decarbonylation reaction, followed by condensation of dialdehyde 3cis with various aminophenols. The influence of the substituents on the ligands on the Pinacol Coupling reaction was investigated. As a result, the reductive Coupling reaction between aliphatic and aromatic aldehydes by using a catalytic amount of 1cis in the presence of Me3 SiCl and Zn provided the corresponding cross-coupled 1,2-diol in good yields with high cross-selectivity.
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synthesis of three dimensionally arranged bis biphenol ligand on hexaaryl benzene scaffold and its application for cross Pinacol Coupling reaction
Tetrahedron Letters, 2011Co-Authors: Toru Amaya, Akihiro Miyasaka, Toshikazu HiraoAbstract:Abstract The three-dimensionally arranged bis-biphenol ligand on a hexaaryl benzene scaffold for a dinuclear complex was synthesized by the Diels–Alder addition–decarbonylation reaction as a key step. Its preliminary studies on the titanium-induced cross-Pinacol Coupling reaction were performed based on step-by-step activation of two different aldehydes.
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Vanadium-catalyzed Pinacol Coupling reaction in water.
The Journal of organic chemistry, 2005Co-Authors: Toshikazu HiraoAbstract:A catalytic Pinacol Coupling using water as a solvent was performed by a catalytic amount of vanadium(III) chloride and metallic Al as a co-reductant. A combination forms a binary catalytic system, being in sharp contrast to the reaction in organic solvent, which requires a chlorosilane as an additive. Various aromatic aldehydes underwent the reductive Coupling to give the corresponding 1,2-diols in moderate to good yields.
Muriel Billamboz - One of the best experts on this subject based on the ideXlab platform.
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Selective Pinacol-Coupling Reaction using a Continuous Flow System
The Journal of organic chemistry, 2016Co-Authors: Nicolas Sotto, Muriel Billamboz, Clément Cazorla, Carole Villette, Christophe LenAbstract:The first continuous flow Pinacol Coupling reaction of carbonyl compounds was successfully achieved within only 2 min during a single pass through a cartridge filled with zinc(0). The optimized method allowed the efficient production of gram-scale value-added compounds with high productivity. The developed methodology is efficient for aromatic or α,β-unsaturated aldehydes but gives moderate results for more stable acetophenone derivatives. Moreover, the flow method displayed better results in terms of yield and selectivity in comparison to the corresponding batch methodology.
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Selective Pinacol-Coupling Reaction using a Continuous Flow System
2016Co-Authors: Nicolas Sotto, Muriel Billamboz, Carole Villette, Clément Cazorla, Christophe LenAbstract:The first continuous flow Pinacol Coupling reaction of carbonyl compounds was successfully achieved within only 2 min during a single pass through a cartridge filled with zinc(0). The optimized method allowed the efficient production of gram-scale value-added compounds with high productivity. The developed methodology is efficient for aromatic or α,β-unsaturated aldehydes but gives moderate results for more stable acetophenone derivatives. Moreover, the flow method displayed better results in terms of yield and selectivity in comparison to the corresponding batch methodology
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Selective Pinacol Coupling on Regeneratable Supported Acids in Sole Water
The Journal of organic chemistry, 2015Co-Authors: Nicolas Sotto, Muriel Billamboz, Carole Chevrin-villette, Christophe LenAbstract:Efficient Pinacol Coupling was developed in sole water, using a reusable heterogeneous supported acid source and zinc as cheap available metal source. This medium can be easily regenerated up to 10-fold without loss of activity. Moreover, supported acids enhance the selectivity of the Pinacol Coupling reaction compared with homogeneous acids.
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simple and expeditious Pinacol Coupling of non usual α β unsaturated carbonyl compounds in water
RSC Advances, 2015Co-Authors: Muriel Billamboz, Nicolas Sotto, Christophe Len, Carole ChevrinvilletteAbstract:Using zinc (0) in a 5% v AcOH aqueous solution allowed the efficient Pinacol Coupling of aliphatic or aromatic unusual, α,β-unsaturated carbonyl compounds such as citral A in good to excellent yields (56–99%). It can also be successfully applied to acetophenone.
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First Pinacol Coupling in Emulsified Water: Key Role of Surfactant and Impact of Alternative Activation Technologies
ChemSusChem, 2015Co-Authors: Muriel Billamboz, Christophe LenAbstract:For the first time, the influence of surfactants on the radical Pinacol Coupling reaction is investigated. The rate and selectivity of this reductive C-C Coupling are compared under three different activation technologies: thermal activation, microwave irradiation, and sonication. The use of IgepalCO520, a neutral surfactant, led to the successful conversion of aromatic or α,β-unsaturated aliphatic carbonyl compounds in moderate to excellent yield (55-90 %). An insight on the potential mechanism involved in the reaction is also proposed, based on microscopic observations and particle size measurement.
Jiwu Wen - One of the best experts on this subject based on the ideXlab platform.
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novel tetradentate bisoxazoline ligands from l serine and β ddb for asymmetric Pinacol Coupling reactions of aromatic aldehydes
ChemInform, 2013Co-Authors: Jiwu Wen, Limin Liu, Xiaochun ZhouAbstract:A series of novel hydroxyl-containing tetradentate bisoxazolines are synthesized and successfully applied as chiral ligands in the asymmetric Pinacol Coupling of aromatic aldehydes (8 examples).
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Novel tetradentate bisoxazoline ligands from l-serine and β-DDB for asymmetric Pinacol Coupling reactions of aromatic aldehydes
Tetrahedron-asymmetry, 2013Co-Authors: Jiwu Wen, Limin Liu, Xiaochun ZhouAbstract:Abstract A variety of novel hydroxyl-containing tetradentate bisoxazolines were successfully synthesized from natural l -serine and β-DDB. The applications of these ligands in the asymmetric Pinacol Coupling of aromatic aldehydes revealed that the absolute configurations of the resulting Pinacols were entirely dominated by the axial chirality of the biphenyl component and that the bulky substituent adjacent to the hydroxyl group was favorable for achieving both high diastereoselectivities and enantioselectivities. Among the ligands screened, (S,aR,S)-1c exhibited much better asymmetric induction capacity to furnish the (R,R)-Pinacols with diastereoselectivities up to 99/1 and with 63–89% enantiomeric excess. A plausible mechanism of the asymmetric Pinacol Coupling was also suggested.
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Biphenyl-oxazoline ligands derived from β-DDB: Their synthesis and application in asymmetric Pinacol Coupling reaction
Journal of Molecular Catalysis A-chemical, 2006Co-Authors: Jiwu Wen, Qitao Tan, Tianpa YouAbstract:Biphenyl-bisoxazoline ligands conveniently synthesized from β-DDB have been exploited in asymmetric Pinacol Coupling reaction for the first time. The Pinacol products were obtained with good yields, high diastereoselectivities and good enantioselectivities (up to 83%e.e.). The stereochemistry of the diol products was dominated by the steric structure of the oxazoline component. Ligands bearing bulky groups in the chiral centre of the oxazolines showed more efficient for achieving both high diastereoselectivity and enantioselectivity.
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Asymmetric Pinacol Coupling catalyzed by TADDOL-titanium complexes
Journal of Molecular Catalysis A-chemical, 2005Co-Authors: Jiwu Wen, Jun Zhao, Tianpa YouAbstract:Abstract Chiral diols 1–4 derived from tartaric acid have been exploited in asymmetry Pinacol Coupling reaction, good to excellent diastereoselectivities and moderate to good enantioselectivities were obtained.