The Experts below are selected from a list of 11943 Experts worldwide ranked by ideXlab platform
Eric N Jacobsen - One of the best experts on this subject based on the ideXlab platform.
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highly Enantioselective direct conjugate addition of ketones to nitroalkenes promoted by a chiral primary amine thiourea Catalyst
Journal of the American Chemical Society, 2006Co-Authors: Hongbing Huang, Eric N JacobsenAbstract:Primary amine−thiourea derivative 1 is an active and highly Enantioselective Catalyst for the conjugate addition of ketones to nitroalkenes. Broad substrate scope is described, with nitroalkenes bearing either aromatic or aliphatic substituents and a wide variety of ketones shown to be useful reacting partners. Ethyl ketones react preferentially, generating anti products with methyl-bearing stereocenters with good-to-excellent diastereoselectivity. An enamine mechanism is indicated, with cooperative activation of the electrophile by the thiourea and of the ketone by the primary amine.
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highly Enantioselective direct conjugate addition of ketones to nitroalkenes promoted by a chiral primary amine thiourea Catalyst
Journal of the American Chemical Society, 2006Co-Authors: Hongbing Huang, Eric N JacobsenAbstract:Primary amine−thiourea derivative 1 is an active and highly Enantioselective Catalyst for the conjugate addition of ketones to nitroalkenes. Broad substrate scope is described, with nitroalkenes be...
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structure based analysis and optimization of a highly Enantioselective Catalyst for the strecker reaction
Journal of the American Chemical Society, 2002Co-Authors: Petr Vachal, Eric N JacobsenAbstract:A mechanistic investigation of the asymmetric Strecker reaction catalyzed by a metal-free Schiff base Catalyst was conducted. The active site of the Catalyst, the relevant stereoisomer of the imine substrate, and the solution structure of the imine−Catalyst complex were elucidated using a series of kinetics, structure−activity, and NMR experiments. An unusual bridging interaction between the imine and the urea hydrogens of the Catalyst was identified and supported by computation. Rational optimization of Catalyst structure based on the mechanistic insight led to an improved Catalyst for the asymmetric Strecker reaction.
Genehsian Lee - One of the best experts on this subject based on the ideXlab platform.
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camphor based schiff base ligand sbaib an Enantioselective Catalyst for addition of phenylacetylene to aldehydes
ChemInform, 2012Co-Authors: Ramalingam Boobalan, Chinpiao Chen, Genehsian LeeAbstract:The ligand derived from (1R)-camphor is an excellent Catalyst for the synthesis of (R)-propargylic alcohols from aromatic, heteroaromatic, and aliphatic aldehydes.
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camphor based schiff base ligand sbaib an Enantioselective Catalyst for addition of phenylacetylene to aldehydes
Organic and Biomolecular Chemistry, 2012Co-Authors: Ramalingam Boobalan, Chinpiao Chen, Genehsian LeeAbstract:A series of Schiff base ligands were synthesized from (1R)-camphor. Under the optimal conditions, (+)-SBAIB-a, 10 was found to be an excellent Catalyst for the Enantioselective addition of phenylacetylene to various aldehydes without utilizing either achiral additives or Ti(OiPr)4. This approach yielded (R)-propargylic alcohols in extremely high yields (up to 99%) and excellent enantioselectivities (up to 92%). The corresponding (S)-propargylic alcohols were synthesized in good to high enantioselectivities (up to 91%) and excellent yields (up to 99%) using (−)-SBAIB-a, 41.
Hongbing Huang - One of the best experts on this subject based on the ideXlab platform.
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highly Enantioselective direct conjugate addition of ketones to nitroalkenes promoted by a chiral primary amine thiourea Catalyst
Journal of the American Chemical Society, 2006Co-Authors: Hongbing Huang, Eric N JacobsenAbstract:Primary amine−thiourea derivative 1 is an active and highly Enantioselective Catalyst for the conjugate addition of ketones to nitroalkenes. Broad substrate scope is described, with nitroalkenes bearing either aromatic or aliphatic substituents and a wide variety of ketones shown to be useful reacting partners. Ethyl ketones react preferentially, generating anti products with methyl-bearing stereocenters with good-to-excellent diastereoselectivity. An enamine mechanism is indicated, with cooperative activation of the electrophile by the thiourea and of the ketone by the primary amine.
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highly Enantioselective direct conjugate addition of ketones to nitroalkenes promoted by a chiral primary amine thiourea Catalyst
Journal of the American Chemical Society, 2006Co-Authors: Hongbing Huang, Eric N JacobsenAbstract:Primary amine−thiourea derivative 1 is an active and highly Enantioselective Catalyst for the conjugate addition of ketones to nitroalkenes. Broad substrate scope is described, with nitroalkenes be...
Mahnjoo Kim - One of the best experts on this subject based on the ideXlab platform.
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ionic surfactant coated burkholderia cepacia lipase as a highly active and Enantioselective Catalyst for the dynamic kinetic resolution of secondary alcohols
ChemInform, 2012Co-Authors: Hyunjin Kim, Jaiwook Park, Yoon Kyung Choi, Jusuk Lee, Eungyeong Lee, Mahnjoo KimAbstract:The commercially available lipase PS is purified and lyophilized in the presence of an ionic surfactant to provide significantly enhanced activity.
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ionic surfactant coated burkholderia cepacia lipase as a highly active and Enantioselective Catalyst for the dynamic kinetic resolution of secondary alcohols
Angewandte Chemie, 2011Co-Authors: Hyunjin Kim, Jaiwook Park, Yoon Kyung Choi, Jusuk Lee, Eungyeong Lee, Mahnjoo KimAbstract:The widerapplications of these DKR procedures in organic synthesis,however, can be hampered by the narrow specificity, moder-ate enantioselectivity, and low activity of the enzymeemployed. Therefore, it is of great importance to develop ahighly active enzyme having high enantioselectivity toward awide range of substrates for DKR. We herein report thationic-surfactant-coated Burkholderia cepacia lipase(ISCBCL) has great potential as such an excellent enzyme.Commercially available Burkholderia cepacia lipase(BCL; brand names: Lipase PS and Lipase PS-C) displayssignificantly lower activity than Candida antarctica lipase B(CALB; brand name: Novozym 435) (Table 1, entries 1–3);the latter has been most frequently employed in the metallo-enzymatic DKR. Fortunately, we have developed a practicalapproach for enhancing its activity dramatically. In a typicalprocedure, buffer-free soluble BCL (24% protein),
Ramalingam Boobalan - One of the best experts on this subject based on the ideXlab platform.
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camphor based schiff base ligand sbaib an Enantioselective Catalyst for addition of phenylacetylene to aldehydes
ChemInform, 2012Co-Authors: Ramalingam Boobalan, Chinpiao Chen, Genehsian LeeAbstract:The ligand derived from (1R)-camphor is an excellent Catalyst for the synthesis of (R)-propargylic alcohols from aromatic, heteroaromatic, and aliphatic aldehydes.
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camphor based schiff base ligand sbaib an Enantioselective Catalyst for addition of phenylacetylene to aldehydes
Organic and Biomolecular Chemistry, 2012Co-Authors: Ramalingam Boobalan, Chinpiao Chen, Genehsian LeeAbstract:A series of Schiff base ligands were synthesized from (1R)-camphor. Under the optimal conditions, (+)-SBAIB-a, 10 was found to be an excellent Catalyst for the Enantioselective addition of phenylacetylene to various aldehydes without utilizing either achiral additives or Ti(OiPr)4. This approach yielded (R)-propargylic alcohols in extremely high yields (up to 99%) and excellent enantioselectivities (up to 92%). The corresponding (S)-propargylic alcohols were synthesized in good to high enantioselectivities (up to 91%) and excellent yields (up to 99%) using (−)-SBAIB-a, 41.