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Huw M. L. Davies - One of the best experts on this subject based on the ideXlab platform.
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copper ii acetate induced oxidation of hydrazones to diazo compounds under flow conditions followed by dirhodium catalyzed enantioselective Cyclopropanation reactions
Organic Letters, 2021Co-Authors: Bo Wei, Christopher W Jones, Taylor A Hatridge, Huw M. L. DaviesAbstract:A tandem system comprising in-line diazo compound synthesis and downstream consumption in a rhodium-catalyzed Cyclopropanation reaction has been developed. Passing hydrazone through a silica column absorbed with Cu(OAc)2-H2O/N,N-dimethylaminopyridine oxidized the hydrazone to generate an aryldiazoacetate in flow. The crude aryldiazoacetate elutes from this column directly into a downstream Cyclopropanation reaction, catalyzed by the chiral dirhodium tetracarboxylates, Rh2(R-p-Ph-TPCP)4 and Rh2(R-PTAD)4. This convenient flow to batch method was applied to the synthesis of a range of 1,2-diarylcyclopropane-1-carboxylates in high yields and with high levels of enantioselectivity.
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silica immobilized chiral dirhodium ii catalyst for enantioselective carbenoid reactions
ChemInform, 2014Co-Authors: Kathryn M Chepiga, Yan Feng, Nicholas A Brunelli, Christopher W Jones, Huw M. L. DaviesAbstract:An optically active silica supported dirhodium catalyst is prepared and successfully applied to Cyclopropanation, cyclopropenation, tandem ylide formation/[2,3] sigmatropic rearrangement and C-H functionalization reactions.
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silica immobilized chiral dirhodium ii catalyst for enantioselective carbenoid reactions
Organic Letters, 2013Co-Authors: Kathryn M Chepiga, Yan Feng, Nicholas A Brunelli, Christopher W Jones, Huw M. L. DaviesAbstract:A silica-supported dirhodium(II) tetraprolinate catalyst was synthesized in four steps from l-proline and used in a range of enantioselective transformations of donor/acceptor carbenoids. These include cyclopropenation, Cyclopropanation, tandem ylide formation/[2,3] sigmatropic rearrangement, and a variety of combined C–H functionalization/Cope rearrangement reactions. The products of these transformations were obtained in yields and levels of enantioselectivity comparable to those obtained with its homogeneous counterpart, Rh2(S-DOSP)4. The silica-supported Rh2(S-DOSP)4 derivative was successfully recycled over five reactions.
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rhodium catalyzed enantioselective Cyclopropanation of electron deficient alkenes
Chemical Science, 2013Co-Authors: Hengbin Wang, Djamaladdin G Musaev, David M Guptill, Adrian Varela Alvarez, Huw M. L. DaviesAbstract:The rhodium-catalyzed reaction of electron-deficient alkenes with substituted aryldiazoacetates and vinyldiazoacetates results in highly stereoselective Cyclopropanations. With adamantylglycine derived catalyst Rh2(S-TCPTAD)4, high asymmetric induction (up to 98% ee) can be obtained with a range of substrates. Computational studies suggest that the reaction is facilitated by weak interaction between the carbenoid and the substrate carbonyl but subsequently proceeds via different pathways depending on the nature of the carbonyl. Acrylates and acrylamides result in the formation of Cyclopropanation products while the use of unsaturated aldehydes and ketones results in the formation of epoxides.
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d2 symmetric dirhodium catalyst derived from a 1 2 2 triarylcyclopropanecarboxylate ligand design synthesis and application
ChemInform, 2012Co-Authors: Changming Qin, Vyacheslav Boyarskikh, Jorn H Hansen, Kenneth I Hardcastle, Djamaladdin G Musaev, Huw M. L. DaviesAbstract:The new rhodium catalyst (I) is prepared and highly enantioselective Cyclopropanations, tandem Cyclopropanation/Cope rearrangements and a combined C—H functionalization/Cope rearrangement are achieved using this catalyst.
James S. Panek - One of the best experts on this subject based on the ideXlab platform.
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Rhodium(II)-Catalyzed Alkyne Amination of Homopropargylic Sulfamate Esters: Stereoselective Synthesis of Functionalized Norcaradienes by Arene Cyclopropanation
2014Co-Authors: Ryan A. Brawn, Kaicheng Zhu, James S. PanekAbstract:A rhodium(II) catalyzed nitrene–alkyne cycloaddition of stereochemically well-defined homopropargylic ethers is followed by arene Cyclopropanation to afford unique tetracyclic norcaradiene products bearing a cyclic sulfamate. Products from the arene Cyclopropanation (Buchner reaction) can be converted to fused cycloheptatrienes via a ring enlarging electrocyclization after nucleophilic ring opening of the cyclic sulfamate ester
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Rhodium(II)-catalyzed alkyne amination of homopropargylic sulfamate esters: stereoselective synthesis of functionalized norcaradienes by arene Cyclopropanation.
Organic Letters, 2013Co-Authors: Ryan A. Brawn, Kaicheng Zhu, James S. PanekAbstract:A rhodium(II) catalyzed nitrene–alkyne cycloaddition of stereochemically well-defined homopropargylic ethers is followed by arene Cyclopropanation to afford unique tetracyclic norcaradiene products bearing a cyclic sulfamate. Products from the arene Cyclopropanation (Buchner reaction) can be converted to fused cycloheptatrienes via a ring enlarging electrocyclization after nucleophilic ring opening of the cyclic sulfamate ester.
Christopher W Jones - One of the best experts on this subject based on the ideXlab platform.
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copper ii acetate induced oxidation of hydrazones to diazo compounds under flow conditions followed by dirhodium catalyzed enantioselective Cyclopropanation reactions
Organic Letters, 2021Co-Authors: Bo Wei, Christopher W Jones, Taylor A Hatridge, Huw M. L. DaviesAbstract:A tandem system comprising in-line diazo compound synthesis and downstream consumption in a rhodium-catalyzed Cyclopropanation reaction has been developed. Passing hydrazone through a silica column absorbed with Cu(OAc)2-H2O/N,N-dimethylaminopyridine oxidized the hydrazone to generate an aryldiazoacetate in flow. The crude aryldiazoacetate elutes from this column directly into a downstream Cyclopropanation reaction, catalyzed by the chiral dirhodium tetracarboxylates, Rh2(R-p-Ph-TPCP)4 and Rh2(R-PTAD)4. This convenient flow to batch method was applied to the synthesis of a range of 1,2-diarylcyclopropane-1-carboxylates in high yields and with high levels of enantioselectivity.
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silica immobilized chiral dirhodium ii catalyst for enantioselective carbenoid reactions
ChemInform, 2014Co-Authors: Kathryn M Chepiga, Yan Feng, Nicholas A Brunelli, Christopher W Jones, Huw M. L. DaviesAbstract:An optically active silica supported dirhodium catalyst is prepared and successfully applied to Cyclopropanation, cyclopropenation, tandem ylide formation/[2,3] sigmatropic rearrangement and C-H functionalization reactions.
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silica immobilized chiral dirhodium ii catalyst for enantioselective carbenoid reactions
Organic Letters, 2013Co-Authors: Kathryn M Chepiga, Yan Feng, Nicholas A Brunelli, Christopher W Jones, Huw M. L. DaviesAbstract:A silica-supported dirhodium(II) tetraprolinate catalyst was synthesized in four steps from l-proline and used in a range of enantioselective transformations of donor/acceptor carbenoids. These include cyclopropenation, Cyclopropanation, tandem ylide formation/[2,3] sigmatropic rearrangement, and a variety of combined C–H functionalization/Cope rearrangement reactions. The products of these transformations were obtained in yields and levels of enantioselectivity comparable to those obtained with its homogeneous counterpart, Rh2(S-DOSP)4. The silica-supported Rh2(S-DOSP)4 derivative was successfully recycled over five reactions.
Djamaladdin G Musaev - One of the best experts on this subject based on the ideXlab platform.
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rhodium catalyzed enantioselective Cyclopropanation of electron deficient alkenes
Chemical Science, 2013Co-Authors: Hengbin Wang, Djamaladdin G Musaev, David M Guptill, Adrian Varela Alvarez, Huw M. L. DaviesAbstract:The rhodium-catalyzed reaction of electron-deficient alkenes with substituted aryldiazoacetates and vinyldiazoacetates results in highly stereoselective Cyclopropanations. With adamantylglycine derived catalyst Rh2(S-TCPTAD)4, high asymmetric induction (up to 98% ee) can be obtained with a range of substrates. Computational studies suggest that the reaction is facilitated by weak interaction between the carbenoid and the substrate carbonyl but subsequently proceeds via different pathways depending on the nature of the carbonyl. Acrylates and acrylamides result in the formation of Cyclopropanation products while the use of unsaturated aldehydes and ketones results in the formation of epoxides.
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d2 symmetric dirhodium catalyst derived from a 1 2 2 triarylcyclopropanecarboxylate ligand design synthesis and application
ChemInform, 2012Co-Authors: Changming Qin, Vyacheslav Boyarskikh, Jorn H Hansen, Kenneth I Hardcastle, Djamaladdin G Musaev, Huw M. L. DaviesAbstract:The new rhodium catalyst (I) is prepared and highly enantioselective Cyclopropanations, tandem Cyclopropanation/Cope rearrangements and a combined C—H functionalization/Cope rearrangement are achieved using this catalyst.
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d2 symmetric dirhodium catalyst derived from a 1 2 2 triarylcyclopropanecarboxylate ligand design synthesis and application
Journal of the American Chemical Society, 2011Co-Authors: Changming Qin, Vyacheslav Boyarskikh, Jorn H Hansen, Kenneth I Hardcastle, Djamaladdin G Musaev, Huw M. L. DaviesAbstract:Dirhodium tetrakis-(R)-(1-(4-bromophenyl)-2,2-diphenylcyclopropanecarboxylate) (Rh2(R-BTPCP)4) was found to be an effective chiral catalyst for enantioselective reactions of aryl- and styryldiazoacetates. Highly enantioselective Cyclopropanations, tandem Cyclopropanation/Cope rearrangements and a combined C–H functionalization/Cope rearrangement were achieved using Rh2(R-BTPCP)4 as catalyst. The advantages of Rh2(R-BTPCP)4 include its ease of synthesis, its tolerance to the size of the ester group in the styryldiazoacetates, and its compatibility with dichloromethane as solvent. Computational studies suggest that the catalyst adopts a D2-symmetric arrangement, but when the carbenoid binds to the catalyst, two of the p-bromophenyl groups on the ligands rotate outward to make room for the carbenoid and the approach of the substrate to the carbenoid.
Ryan A. Brawn - One of the best experts on this subject based on the ideXlab platform.
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Rhodium(II)-Catalyzed Alkyne Amination of Homopropargylic Sulfamate Esters: Stereoselective Synthesis of Functionalized Norcaradienes by Arene Cyclopropanation
2014Co-Authors: Ryan A. Brawn, Kaicheng Zhu, James S. PanekAbstract:A rhodium(II) catalyzed nitrene–alkyne cycloaddition of stereochemically well-defined homopropargylic ethers is followed by arene Cyclopropanation to afford unique tetracyclic norcaradiene products bearing a cyclic sulfamate. Products from the arene Cyclopropanation (Buchner reaction) can be converted to fused cycloheptatrienes via a ring enlarging electrocyclization after nucleophilic ring opening of the cyclic sulfamate ester
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Rhodium(II)-catalyzed alkyne amination of homopropargylic sulfamate esters: stereoselective synthesis of functionalized norcaradienes by arene Cyclopropanation.
Organic Letters, 2013Co-Authors: Ryan A. Brawn, Kaicheng Zhu, James S. PanekAbstract:A rhodium(II) catalyzed nitrene–alkyne cycloaddition of stereochemically well-defined homopropargylic ethers is followed by arene Cyclopropanation to afford unique tetracyclic norcaradiene products bearing a cyclic sulfamate. Products from the arene Cyclopropanation (Buchner reaction) can be converted to fused cycloheptatrienes via a ring enlarging electrocyclization after nucleophilic ring opening of the cyclic sulfamate ester.
