The Experts below are selected from a list of 2814 Experts worldwide ranked by ideXlab platform
Dipak S Dalal - One of the best experts on this subject based on the ideXlab platform.
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β cyclodextrin a green and efficient Supramolecular Catalyst for organic transformations
Chemical Record, 2018Co-Authors: Dipak S Dalal, Dipak R Patil, Yogesh A TayadeAbstract:β-Cyclodextrin is cyclic oligosaccharide possessing hydrophobic cavity, which binds the substrates selectively and catalyze number of organic transformations with high selectivity. It catalyzes the reaction by non-covalent Supramolecular bonding with reversible formation of host-guest complexes as seen in enzymes. This account summarizes our efforts in designing a good number of important organic transformations using β-cyclodextrin and its derivatives. These reactions were performed in neat, aqueous as well as organic media. Greener synthetic routes to a variety of biologically relevant organic molecules has been developed. The temperature, solvent and Catalyst amount plays in important role in these reactions. β-Cyclodextrin activates variety of organic compounds like aldehydes, ketones, anhydride, oximes, amines, nitriles and increases the rate of reactions.
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β-Cyclodextrin as a Supramolecular Catalyst for the Synthesis of 1H-Pyrazolo[1,2-b]phthalazine-5,10-dione Derivatives in Water
Catalysis Letters, 2017Co-Authors: Yogesh A Tayade, Dipak S DalalAbstract:An efficient and green method has been developed for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones derivatives by employing 20 mol% β-cyclodextrin via a one-pot multicomponent reaction of aldehydes, malononitrile and phthalhydrazide in H_2O–EtOH (4:1) at 100 °C for first time under neutral condition. The Catalyst could be recovered and reused for four consecutive cycles without appreciable loss in catalytic activity. Graphical Abstract
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β cyclodextrin as a Supramolecular Catalyst for the synthesis of dihydropyrano 2 3 c pyrazole and spiro indoline 3 4 pyrano 2 3 c pyrazole in aqueous medium
ChemInform, 2015Co-Authors: Yogesh A Tayade, Swapnil A Padvi, Yogesh B Wagh, Dipak S DalalAbstract:The methodology is advantageous with regards to higher yields of products, short reaction times, and neutral reaction conditions.
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β cyclodextrin as a Supramolecular Catalyst for the synthesis of dihydropyrano 2 3 c pyrazole and spiro indoline 3 4 pyrano 2 3 c pyrazole in aqueous medium
Tetrahedron Letters, 2015Co-Authors: Yogesh A Tayade, Swapnil A Padvi, Yogesh B Wagh, Dipak S DalalAbstract:Abstract Supramolecular β-cyclodextrin (β-CD) as a highly efficient, biodegradable, and reusable Catalyst for the synthesis of pyranopyrazole derivatives is investigated via a one-pot four component reaction of aldehydes and isatins, hydrazine hydrate, malononitrile, and β-keto ester in H 2 O–EtOH (9:1) at 80 °C for first time under neutral conditions.
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an efficient synthesis of 3 indolyl 3 hydroxy oxindoles and 3 3 di indolyl indolin 2 ones catalyzed by sulfonated β cd as a Supramolecular Catalyst in water
Tetrahedron Letters, 2015Co-Authors: Yogesh A Tayade, Dipak R Patil, Yogesh B Wagh, Asha D Jangle, Dipak S DalalAbstract:Sulfonated-β-cyclodextrin (β-CD-SO3H) promoted efficient and fast electrophilic substitution reaction of indoles with various isatins reflux in water is reported affording various 3-indolyl-3-hydroxy oxindoles and 3,3-di(indolyl)indolin-2-ones in good to excellent yields in short reaction time.
Yogesh A Tayade - One of the best experts on this subject based on the ideXlab platform.
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β cyclodextrin a green and efficient Supramolecular Catalyst for organic transformations
Chemical Record, 2018Co-Authors: Dipak S Dalal, Dipak R Patil, Yogesh A TayadeAbstract:β-Cyclodextrin is cyclic oligosaccharide possessing hydrophobic cavity, which binds the substrates selectively and catalyze number of organic transformations with high selectivity. It catalyzes the reaction by non-covalent Supramolecular bonding with reversible formation of host-guest complexes as seen in enzymes. This account summarizes our efforts in designing a good number of important organic transformations using β-cyclodextrin and its derivatives. These reactions were performed in neat, aqueous as well as organic media. Greener synthetic routes to a variety of biologically relevant organic molecules has been developed. The temperature, solvent and Catalyst amount plays in important role in these reactions. β-Cyclodextrin activates variety of organic compounds like aldehydes, ketones, anhydride, oximes, amines, nitriles and increases the rate of reactions.
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β-Cyclodextrin as a Supramolecular Catalyst for the Synthesis of 1H-Pyrazolo[1,2-b]phthalazine-5,10-dione Derivatives in Water
Catalysis Letters, 2017Co-Authors: Yogesh A Tayade, Dipak S DalalAbstract:An efficient and green method has been developed for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones derivatives by employing 20 mol% β-cyclodextrin via a one-pot multicomponent reaction of aldehydes, malononitrile and phthalhydrazide in H_2O–EtOH (4:1) at 100 °C for first time under neutral condition. The Catalyst could be recovered and reused for four consecutive cycles without appreciable loss in catalytic activity. Graphical Abstract
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β cyclodextrin as a Supramolecular Catalyst for the synthesis of dihydropyrano 2 3 c pyrazole and spiro indoline 3 4 pyrano 2 3 c pyrazole in aqueous medium
ChemInform, 2015Co-Authors: Yogesh A Tayade, Swapnil A Padvi, Yogesh B Wagh, Dipak S DalalAbstract:The methodology is advantageous with regards to higher yields of products, short reaction times, and neutral reaction conditions.
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β cyclodextrin as a Supramolecular Catalyst for the synthesis of dihydropyrano 2 3 c pyrazole and spiro indoline 3 4 pyrano 2 3 c pyrazole in aqueous medium
Tetrahedron Letters, 2015Co-Authors: Yogesh A Tayade, Swapnil A Padvi, Yogesh B Wagh, Dipak S DalalAbstract:Abstract Supramolecular β-cyclodextrin (β-CD) as a highly efficient, biodegradable, and reusable Catalyst for the synthesis of pyranopyrazole derivatives is investigated via a one-pot four component reaction of aldehydes and isatins, hydrazine hydrate, malononitrile, and β-keto ester in H 2 O–EtOH (9:1) at 80 °C for first time under neutral conditions.
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an efficient synthesis of 3 indolyl 3 hydroxy oxindoles and 3 3 di indolyl indolin 2 ones catalyzed by sulfonated β cd as a Supramolecular Catalyst in water
Tetrahedron Letters, 2015Co-Authors: Yogesh A Tayade, Dipak R Patil, Yogesh B Wagh, Asha D Jangle, Dipak S DalalAbstract:Sulfonated-β-cyclodextrin (β-CD-SO3H) promoted efficient and fast electrophilic substitution reaction of indoles with various isatins reflux in water is reported affording various 3-indolyl-3-hydroxy oxindoles and 3,3-di(indolyl)indolin-2-ones in good to excellent yields in short reaction time.
Yogesh B Wagh - One of the best experts on this subject based on the ideXlab platform.
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β cyclodextrin as a Supramolecular Catalyst for the synthesis of dihydropyrano 2 3 c pyrazole and spiro indoline 3 4 pyrano 2 3 c pyrazole in aqueous medium
ChemInform, 2015Co-Authors: Yogesh A Tayade, Swapnil A Padvi, Yogesh B Wagh, Dipak S DalalAbstract:The methodology is advantageous with regards to higher yields of products, short reaction times, and neutral reaction conditions.
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β cyclodextrin as a Supramolecular Catalyst for the synthesis of dihydropyrano 2 3 c pyrazole and spiro indoline 3 4 pyrano 2 3 c pyrazole in aqueous medium
Tetrahedron Letters, 2015Co-Authors: Yogesh A Tayade, Swapnil A Padvi, Yogesh B Wagh, Dipak S DalalAbstract:Abstract Supramolecular β-cyclodextrin (β-CD) as a highly efficient, biodegradable, and reusable Catalyst for the synthesis of pyranopyrazole derivatives is investigated via a one-pot four component reaction of aldehydes and isatins, hydrazine hydrate, malononitrile, and β-keto ester in H 2 O–EtOH (9:1) at 80 °C for first time under neutral conditions.
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an efficient synthesis of 3 indolyl 3 hydroxy oxindoles and 3 3 di indolyl indolin 2 ones catalyzed by sulfonated β cd as a Supramolecular Catalyst in water
Tetrahedron Letters, 2015Co-Authors: Yogesh A Tayade, Dipak R Patil, Yogesh B Wagh, Asha D Jangle, Dipak S DalalAbstract:Sulfonated-β-cyclodextrin (β-CD-SO3H) promoted efficient and fast electrophilic substitution reaction of indoles with various isatins reflux in water is reported affording various 3-indolyl-3-hydroxy oxindoles and 3,3-di(indolyl)indolin-2-ones in good to excellent yields in short reaction time.
Kenneth N. Raymond - One of the best experts on this subject based on the ideXlab platform.
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Deconvoluting the Role of Charge in a Supramolecular Catalyst
2018Co-Authors: Cynthia M. Hong, Robert G. Bergman, Kenneth N. Raymond, Mariko Morimoto, Eugene A Kapustin, Nicola Alzakhem, Dean F. TosteAbstract:We have demonstrated that the microenvironment of a highly anionic Supramolecular Catalyst can mimic the active sites of enzymes and impart rate accelerations of a million-fold or more. However, these microenvironments can be challenging to study, especially in the context of understanding which specific features of the Catalyst are responsible for its high performance. We report here the development of an experimental mechanistic probe consisting of two isostructural Catalysts. When examined in parallel transformations, the behavior of these Catalysts provides insight relevant to the importance of anionic host charge on reactivity. These two Catalysts exhibit similar host-substrate interactions, but feature a significant difference in overall anionic charge (12– and 8–). Within these systems, we compare the effect of constrictive binding in a net neutral aza-Cope rearrangement. We then demonstrate how the magnitude of anionic host charge has an exceptional influence on the reaction rates for a Nazarov cyclization, evidenced by an impressive 680-fold change in reaction rate as a consequence of a 33% reduction in Catalyst charge
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selective monoterpene like cyclization reactions achieved by water exclusion from reactive intermediates in a Supramolecular Catalyst
Journal of the American Chemical Society, 2012Co-Authors: William M Hartcooper, Robert G. Bergman, Dean F. Toste, Kristen N Clary, Kenneth N. RaymondAbstract:A polyanionic Supramolecular assembly (1) is shown to catalytically cyclize the monoterpene citronellal and two homologues. In contrast to cyclization in acidic aqueous solution, the hydrophobic interior of 1 prevents the capture of reactive intermediates by water. This effect was also observed in the gold-catalyzed cycloisomerization of an enyne. Due to the steric confinement of the Catalyst’s interior, Prins cyclizations in 1 proceed cleanly both for substrates containing and lacking gem-dimethyl substitution. Encapsulation in 1 consequently imposes a degree of mechanistic control that, similar to enzyme catalysis, is not observed in bulk aqueous solution.
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High-Turnover Supramolecular Catalysis by a Protected Ruthenium(II) Complex in Aqueous Solution
Journal of the American Chemical Society, 2011Co-Authors: Casey J Brown, Robert G. Bergman, Gregory M. Miller, Miles W. Johnson, Kenneth N. RaymondAbstract:The design of a Supramolecular Catalyst capable of high-turnover catalysis is reported. A ruthenium(II) Catalyst is incorporated into a water-soluble Supramolecular assembly, imparting the ability to catalyze allyl alcohol isomerization. The Catalyst is protected from decomposition by sequestration inside the host but retains its catalytic activity with scope governed by confinement within the host. This host–guest complex is a uniquely active Supramolecular Catalyst, capable of >1000 turnovers.
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enantioselective catalysis of the aza cope rearrangement by a chiral Supramolecular assembly
Journal of the American Chemical Society, 2009Co-Authors: Casey J Brown, Robert G. Bergman, Kenneth N. RaymondAbstract:The chiral Supramolecular Catalyst Ga4L6 [L = 1,5-bis(2,3-dihydroxybenzoylamino)naphthalene] is a molecular tetrahedron that catalyzes the 3-aza-Cope rearrangement of allyl enammonium cations. This catalysis is accomplished by preorganizing the substrate in a reactive conformation within the host. This work demonstrates that through the use of enantiopure assembly, its chiral cavity is capable of catalyzing the 3-aza-Cope rearrangement enantioselectively, with yields of 21−74% and enantiomeric excesses from 6 to 64% at 50 °C. At lower temperatures, the enantioselectivity improved, reaching 78% ee at 5 °C. This is the highest enantioselectivity to date induced by the chiral cavity of a Supramolecular assembly.
Robert G. Bergman - One of the best experts on this subject based on the ideXlab platform.
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deconvoluting the role of charge in a Supramolecular Catalyst
Journal of the American Chemical Society, 2018Co-Authors: Robert G. Bergman, Cynthia M Hong, Mariko Morimoto, Eugene A Kapustin, Nicola AlzakhemAbstract:We have demonstrated that the microenvironment of a highly anionic Supramolecular Catalyst can mimic the active sites of enzymes and impart rate accelerations of a million-fold or more. However, these microenvironments can be challenging to study, especially in the context of understanding which specific features of the Catalyst are responsible for its high performance. We report here the development of an experimental mechanistic probe consisting of two isostructural Catalysts. When examined in parallel transformations, the behavior of these Catalysts provides insight relevant to the importance of anionic host charge on reactivity. These two Catalysts exhibit similar host-substrate interactions, but feature a significant difference in overall anionic charge (12– and 8–). Within these systems, we compare the effect of constrictive binding in a net neutral aza-Cope rearrangement. We then demonstrate how the magnitude of anionic host charge has an exceptional influence on the reaction rates for a Nazarov cy...
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Deconvoluting the Role of Charge in a Supramolecular Catalyst
2018Co-Authors: Cynthia M. Hong, Robert G. Bergman, Kenneth N. Raymond, Mariko Morimoto, Eugene A Kapustin, Nicola Alzakhem, Dean F. TosteAbstract:We have demonstrated that the microenvironment of a highly anionic Supramolecular Catalyst can mimic the active sites of enzymes and impart rate accelerations of a million-fold or more. However, these microenvironments can be challenging to study, especially in the context of understanding which specific features of the Catalyst are responsible for its high performance. We report here the development of an experimental mechanistic probe consisting of two isostructural Catalysts. When examined in parallel transformations, the behavior of these Catalysts provides insight relevant to the importance of anionic host charge on reactivity. These two Catalysts exhibit similar host-substrate interactions, but feature a significant difference in overall anionic charge (12– and 8–). Within these systems, we compare the effect of constrictive binding in a net neutral aza-Cope rearrangement. We then demonstrate how the magnitude of anionic host charge has an exceptional influence on the reaction rates for a Nazarov cyclization, evidenced by an impressive 680-fold change in reaction rate as a consequence of a 33% reduction in Catalyst charge
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selective monoterpene like cyclization reactions achieved by water exclusion from reactive intermediates in a Supramolecular Catalyst
Journal of the American Chemical Society, 2012Co-Authors: William M Hartcooper, Robert G. Bergman, Dean F. Toste, Kristen N Clary, Kenneth N. RaymondAbstract:A polyanionic Supramolecular assembly (1) is shown to catalytically cyclize the monoterpene citronellal and two homologues. In contrast to cyclization in acidic aqueous solution, the hydrophobic interior of 1 prevents the capture of reactive intermediates by water. This effect was also observed in the gold-catalyzed cycloisomerization of an enyne. Due to the steric confinement of the Catalyst’s interior, Prins cyclizations in 1 proceed cleanly both for substrates containing and lacking gem-dimethyl substitution. Encapsulation in 1 consequently imposes a degree of mechanistic control that, similar to enzyme catalysis, is not observed in bulk aqueous solution.
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High-Turnover Supramolecular Catalysis by a Protected Ruthenium(II) Complex in Aqueous Solution
Journal of the American Chemical Society, 2011Co-Authors: Casey J Brown, Robert G. Bergman, Gregory M. Miller, Miles W. Johnson, Kenneth N. RaymondAbstract:The design of a Supramolecular Catalyst capable of high-turnover catalysis is reported. A ruthenium(II) Catalyst is incorporated into a water-soluble Supramolecular assembly, imparting the ability to catalyze allyl alcohol isomerization. The Catalyst is protected from decomposition by sequestration inside the host but retains its catalytic activity with scope governed by confinement within the host. This host–guest complex is a uniquely active Supramolecular Catalyst, capable of >1000 turnovers.
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enantioselective catalysis of the aza cope rearrangement by a chiral Supramolecular assembly
Journal of the American Chemical Society, 2009Co-Authors: Casey J Brown, Robert G. Bergman, Kenneth N. RaymondAbstract:The chiral Supramolecular Catalyst Ga4L6 [L = 1,5-bis(2,3-dihydroxybenzoylamino)naphthalene] is a molecular tetrahedron that catalyzes the 3-aza-Cope rearrangement of allyl enammonium cations. This catalysis is accomplished by preorganizing the substrate in a reactive conformation within the host. This work demonstrates that through the use of enantiopure assembly, its chiral cavity is capable of catalyzing the 3-aza-Cope rearrangement enantioselectively, with yields of 21−74% and enantiomeric excesses from 6 to 64% at 50 °C. At lower temperatures, the enantioselectivity improved, reaching 78% ee at 5 °C. This is the highest enantioselectivity to date induced by the chiral cavity of a Supramolecular assembly.