The Experts below are selected from a list of 30210 Experts worldwide ranked by ideXlab platform
Shannon S Stahl - One of the best experts on this subject based on the ideXlab platform.
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aerobic dehydrogenation of Cyclohexanone to cyclohexenone catalyzed by pd dmso 2 tfa 2 evidence for ligand controlled chemoselectivity
Journal of the American Chemical Society, 2013Co-Authors: Tianning Diao, Shannon S StahlAbstract:The dehydrogenation of Cyclohexanones affords cyclohexenones or phenols via removal of 1 or 2 equiv of H2, respectively. We recently reported several PdII catalyst systems that effect aerobic dehydrogenation of Cyclohexanones with different product selectivities. Pd(DMSO)2(TFA)2 is unique in its high chemoselectivity for the conversion of Cyclohexanones to cyclohexenones, without promoting subsequent dehydrogenation of cyclohexenones to phenols. Kinetic and mechanistic studies of these reactions reveal the key role of the dimethylsulfoxide (DMSO) ligand in controlling this chemoselectivity. DMSO has minimal kinetic influence on the rate of Pd(TFA)2-catalyzed dehydrogenation of Cyclohexanone to cyclohexenone, while it strongly inhibits the second dehydrogenation step, conversion of cyclohexenone to phenol. These contrasting kinetic effects of DMSO provide the basis for chemoselective formation of cyclohexenones.
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aerobic dehydrogenation of Cyclohexanone to phenol catalyzed by pd tfa 2 2 dimethylaminopyridine evidence for the role of pd nanoparticles
Journal of the American Chemical Society, 2013Co-Authors: Doris Pun, Tianning Diao, Shannon S StahlAbstract:We have carried out a mechanistic investigation of aerobic dehydrogenation of Cyclohexanones and cyclohexenones to phenols with a Pd(TFA)2/2-dimethylaminopyridine catalyst system. Numerous experimental methods, including kinetic studies, filtration tests, Hg poisoning experiments, transmission electron microscopy, and dynamic light scattering, provide compelling evidence that the initial PdII catalyst mediates the first dehydrogenation of Cyclohexanone to cyclohexenone, after which it evolves into soluble Pd nanoparticles that retain catalytic activity. This nanoparticle formation and stabilization is facilitated by each of the components in the catalytic reaction, including the ligand, TsOH, DMSO, substrate, and cyclohexenone intermediate.
Tianning Diao - One of the best experts on this subject based on the ideXlab platform.
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aerobic dehydrogenation of Cyclohexanone to cyclohexenone catalyzed by pd dmso 2 tfa 2 evidence for ligand controlled chemoselectivity
Journal of the American Chemical Society, 2013Co-Authors: Tianning Diao, Shannon S StahlAbstract:The dehydrogenation of Cyclohexanones affords cyclohexenones or phenols via removal of 1 or 2 equiv of H2, respectively. We recently reported several PdII catalyst systems that effect aerobic dehydrogenation of Cyclohexanones with different product selectivities. Pd(DMSO)2(TFA)2 is unique in its high chemoselectivity for the conversion of Cyclohexanones to cyclohexenones, without promoting subsequent dehydrogenation of cyclohexenones to phenols. Kinetic and mechanistic studies of these reactions reveal the key role of the dimethylsulfoxide (DMSO) ligand in controlling this chemoselectivity. DMSO has minimal kinetic influence on the rate of Pd(TFA)2-catalyzed dehydrogenation of Cyclohexanone to cyclohexenone, while it strongly inhibits the second dehydrogenation step, conversion of cyclohexenone to phenol. These contrasting kinetic effects of DMSO provide the basis for chemoselective formation of cyclohexenones.
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aerobic dehydrogenation of Cyclohexanone to phenol catalyzed by pd tfa 2 2 dimethylaminopyridine evidence for the role of pd nanoparticles
Journal of the American Chemical Society, 2013Co-Authors: Doris Pun, Tianning Diao, Shannon S StahlAbstract:We have carried out a mechanistic investigation of aerobic dehydrogenation of Cyclohexanones and cyclohexenones to phenols with a Pd(TFA)2/2-dimethylaminopyridine catalyst system. Numerous experimental methods, including kinetic studies, filtration tests, Hg poisoning experiments, transmission electron microscopy, and dynamic light scattering, provide compelling evidence that the initial PdII catalyst mediates the first dehydrogenation of Cyclohexanone to cyclohexenone, after which it evolves into soluble Pd nanoparticles that retain catalytic activity. This nanoparticle formation and stabilization is facilitated by each of the components in the catalytic reaction, including the ligand, TsOH, DMSO, substrate, and cyclohexenone intermediate.
René Grée - One of the best experts on this subject based on the ideXlab platform.
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Total Synthesis of Gabosines
European Journal of Organic Chemistry, 2012Co-Authors: Dinh Hung Mac, Srivari Chandrasekhar, René GréeAbstract:This review reports on the total synthesis of gabosines, a family of secondary metabolites containing trihydroxylated Cyclohexanone or cyclohexenone cores. Analysis of the different stategies used to prepare these natural products and their stereoisomers has been carried out with special attention paid to the methods employed for the formation of the carbocyclic ring. The different methods are compared in a table, and a discussion of future directions of research in this area is presented.
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Total synthesis of gabosines via an iron-catalyzed intramolecular tandem aldol process
Tetrahedron, 2011Co-Authors: Dinh Hung Mac, Srivari Chandrasekhar, Ramesh Samineni, Abdul Sattar, Jhillu Yadav, René GréeAbstract:Several gabosines, belonging to polyhydroxy-cyclohexenone and Cyclohexanone class of natural products, are synthesized in various stereoforms using an intramolecular iron-catalyzed tandem aldol process. The reaction, which starts from vinylic pyranoses, is compatible with two different OH protecting groups (acetyl and benzyl). Further, like the Ferrier carbocyclisation, it is not sensitive to the stereochemistry of sugar molecules used as precursors: six different gabosine-type molecules have been prepared by this route starting from d-Glucose, d-Mannose, and d-Galactose derivatives.
Chuxiong Chen - One of the best experts on this subject based on the ideXlab platform.
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Solubilities of adipic acid in binary Cyclohexanone + cyclohexanol, cyclohexane + cyclohexanol, and cyclohexane + Cyclohexanone solvent mixtures
Fluid Phase Equilibria, 2016Co-Authors: Xiaoxiao Sheng, Zhenhua Xiong, Qinbo Wang, Chuxiong ChenAbstract:Abstract The solubilities of adipic acid in Cyclohexanone + cyclohexanol mixtures at (303.15–349.45) K, in cyclohexane + cyclohexanol mixtures at (304.15–339.45) K, and in cyclohexane + Cyclohexanone mixtures at (304.85–342.45) K were determined at atmospheric pressure by the dynamic method. Experimental results show that when solvent composition remains constant, solubilities of adipic acid in the studied binary mixed solvents increase monotonically with temperature increasing, and when temperature remains constant, solubilities of adipic acid decrease monotonically with the increasing mass fraction of cyclohexane in cyclohexane + cyclohexanol and cyclohexane + Cyclohexanone mixture. However, the measured solubility firstly increases monotonically with the increasing mass fraction of Cyclohexanone in Cyclohexanone + cyclohexanol mixtures and then reaches the maximum solubility at the mass fraction of Cyclohexanone at 0.4. When the mass fraction of Cyclohexanone was bigger than 0.40, the solubility of adipic acid decreased with the increasing mass fraction of Cyclohexanone. There exists a maximum-solubility effect. Further, both the NRTL equation and the Apelblat equation were used to correlate the experimentally determined solubilities. A fairly good agreement was obtained between the correlated solubilities with the experimental observations. Thermodynamic quantities of dissolution were calculated by the Clark and Glew equation, including dissolution enthalpy, entropy, Gibbs energy and isobaric heat capacity for adicip acid in cyclohexane + cyclohexanol, cyclohexane + Cyclohexanone, and Cyclohexanone + cyclohexanol solvent mixtures.
Dinh Hung Mac - One of the best experts on this subject based on the ideXlab platform.
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Total Synthesis of Gabosines
European Journal of Organic Chemistry, 2012Co-Authors: Dinh Hung Mac, Srivari Chandrasekhar, René GréeAbstract:This review reports on the total synthesis of gabosines, a family of secondary metabolites containing trihydroxylated Cyclohexanone or cyclohexenone cores. Analysis of the different stategies used to prepare these natural products and their stereoisomers has been carried out with special attention paid to the methods employed for the formation of the carbocyclic ring. The different methods are compared in a table, and a discussion of future directions of research in this area is presented.
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Total synthesis of gabosines via an iron-catalyzed intramolecular tandem aldol process
Tetrahedron, 2011Co-Authors: Dinh Hung Mac, Srivari Chandrasekhar, Ramesh Samineni, Abdul Sattar, Jhillu Yadav, René GréeAbstract:Several gabosines, belonging to polyhydroxy-cyclohexenone and Cyclohexanone class of natural products, are synthesized in various stereoforms using an intramolecular iron-catalyzed tandem aldol process. The reaction, which starts from vinylic pyranoses, is compatible with two different OH protecting groups (acetyl and benzyl). Further, like the Ferrier carbocyclisation, it is not sensitive to the stereochemistry of sugar molecules used as precursors: six different gabosine-type molecules have been prepared by this route starting from d-Glucose, d-Mannose, and d-Galactose derivatives.
