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André B. Charette - One of the best experts on this subject based on the ideXlab platform.
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Grob Fragmentation of 2-Azabicyclo[2.2.2]oct-7-ene: Tool for the Stereoselective Synthesis of Polysubstituted Piperidines.
ChemInform, 2012Co-Authors: Gérald Lemonnier, André B. CharetteAbstract:The Grob Fragmentation of bicycles (I) or (XVIII) provides highly reactive dihydropyridinium intermediates which react with a variety of organocuprates or other soft nucleophiles in a regio- and stereoselective manner to give 2,3,4-trisubstituted 1,2,3,4-tetrahydropyridines.
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Grob Fragmentation of 2-azabicyclo[2.2.2]oct-7-ene: tool for the stereoselective synthesis of polysubstituted piperidines.
The Journal of organic chemistry, 2012Co-Authors: Gérald Lemonnier, André B. CharetteAbstract:The Grob Fragmentation of azabicyclo[2.2.2]octene leads to a dihydropyridinium intermediate. This highly reactive species reacts with a variety of organocuprates and other soft nucleophiles in a regioselective manner, allowing for the rapid and stereoselective synthesis of 2,3,4-trisubstituted 1,2,3,4-tetrahydropyridines. The resulting products were either reduced in situ to the corresponding piperidine or used to achieve the stereoselective construction of various nitrogen heterocycles.
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Stereoselective Synthesis of 2,3,6-Trisubstituted Tetrahydropyridines via Tf2O-Mediated Grob Fragmentation: Access to Indolizidines (-)-209I and (-)-223J
The Journal of organic chemistry, 2010Co-Authors: Gérald Lemonnier, André B. CharetteAbstract:Herein we describe the γ-amino hydroxide Grob Fragmentation of the aza-bicyclo[2.2.2]octene 1 using triflic anhydride as the activating agent. The resulting dihydropyridinium ion can react with a wide variety of Grignard reagents, giving access to 2,3,6-trisubstituted tetrahydropyridines (2) with high regio- and stereoselectivities. This methodology has been applied to the short synthesis of natural indolizidines (-)-209I (3) and (-)-223J (4).
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stereoselective synthesis of 2 3 6 trisubstituted tetrahydropyridines via tf2o mediated Grob Fragmentation access to indolizidines 209i and 223j
Journal of Organic Chemistry, 2010Co-Authors: Gérald Lemonnier, André B. CharetteAbstract:Herein we describe the γ-amino hydroxide Grob Fragmentation of the aza-bicyclo[2.2.2]octene 1 using triflic anhydride as the activating agent. The resulting dihydropyridinium ion can react with a wide variety of Grignard reagents, giving access to 2,3,6-trisubstituted tetrahydropyridines (2) with high regio- and stereoselectivities. This methodology has been applied to the short synthesis of natural indolizidines (-)-209I (3) and (-)-223J (4).
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Silver Ion-Induced Grob Fragmentation of γ-Amino Iodides: Highly Stereoselective Synthesis of Polysubstituted Piperidines
Organic letters, 2008Co-Authors: Guillaume Barbe, Miguel St-onge, André B. CharetteAbstract:A new concerted silver ion-mediated Grob Fragmentation process is described in which a 1,2-dihydropyridinium ion is formed and trapped in situ with Grignard reagents in a highly regio- and diastereoselective fashion. Using this methodology, 2,3,6-trisubstituted piperidines were synthesized in good yields and further derivatized to polysubstituted indolizidine.
David Zhigang Wang - One of the best experts on this subject based on the ideXlab platform.
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Tackling Reactivity and Selectivity within a Strained Architecture: Construction of the [6–6–5–7] Tetracyclic Core of Calyciphylline Alkaloids
The Journal of organic chemistry, 2012Co-Authors: Lu Wang, Xiaojiang Hao, David Zhigang WangAbstract:A stereochemically controlled route to the enantiopure [6-6-5-7] tetracyclic core of Calyciphylline A class alkaloids was established, which involves Overman rearrangement, [2 + 2] photochemical cycloaddition, Grob Fragmentation, C-N bond-forming nucleophilic displacement, and ring strain-directed hydrogenation as strategic steps.
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Tackling Reactivity and Selectivity within a Strained Architecture: Construction of the [6–6–5–7] Tetracyclic Core of Calyciphylline Alkaloids
2012Co-Authors: Lu Wang, Xiaojiang Hao, David Zhigang WangAbstract:A stereochemically controlled route to the enantiopure [6–6–5–7] tetracyclic core of Calyciphylline A class alkaloids was established, which involves Overman rearrangement, [2 + 2] photochemical cycloaddition, Grob Fragmentation, C–N bond-forming nucleophilic displacement, and ring strain-directed hydrogenation as strategic steps
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Rapid construction of [5-6-7] tricyclic ring skeleton of Calyciphylline alkaloid daphnilongeranin B.
Organic letters, 2011Co-Authors: Zheng Liu, Huifei Wang, Bo Zhang, Zheng Xiang, Xiaojiang Hao, David Zhigang WangAbstract:A concise photochemical [2 + 2] cycloaddition-Grob Fragmentation sequence sets the common tricyclic ring skeletons of the Calyciphylline A-type alkaloids, particularly those in daphnilongeranins, daphniyunnines, and daphniglaucins.
Wang, David Zhigang - One of the best experts on this subject based on the ideXlab platform.
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Tackling Reactivity and Selectivity within a Strained Architecture: Construction of the [6-6-5-7] Tetracyclic Core of Calyciphylline Alkaloids
journal of organic chemistry, 2012Co-Authors: Xu Chen, Hao Xiaojiang, Lu Wang, Wang, David ZhigangAbstract:A stereochemically controlled route to the enantiopure [6-6-5-7] tetracyclic core of Calyciphylline A class alkaloids was established, which involves Overman rearrangement, [2 + 2] photochemical cycloaddition, Grob Fragmentation, C-N bond-forming nucleophilic displacement, and ring strain-directed hydrogenation as strategic steps.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000306534400046&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Chemistry, OrganicSCI(E)EIPubMed28ARTICLE146307-63137
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Rapid Construction of [5-6-7] Tricyclic Ring Skeleton of Calyciphylline Alkaloid Daphnilongeranin B
organic letters, 2011Co-Authors: Xu Chen, Bo Zhang, Liu Zheng, Wang Huifei, Xiang Zheng, Hao Xiaojiang, Wang, David ZhigangAbstract:A concise photochemical [2 + 2] cycloaddition-Grob Fragmentation sequence sets the common tricyclic ring skeletons of the Calyciphylline A-type alkaloids, particularly those in daphnilongeranins, daphniyunnines, and daphniglaucins.Chemistry, OrganicSCI(E)PubMed23ARTICLE71812-18151
Chun-an Fan - One of the best experts on this subject based on the ideXlab platform.
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Arylation and vinylation of alkenes based on unusual sequential semipinacol rearrangement/Grob Fragmentation of allylic alcohols.
The Journal of organic chemistry, 2008Co-Authors: Dao‐yi Yuan, Chun-an FanAbstract:Alkenes can be stereoselectively arylated and vinylated without transition-metal catalyst under mild conditions through an interesting NBS-promoted semipinacol rearrangement and a subsequent unusual NaOH-mediated Grob Fragmentation.
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arylation and vinylation of alkenes based on unusual sequential semipinacol rearrangement Grob Fragmentation of allylic alcohols
Journal of Organic Chemistry, 2008Co-Authors: Daoyi Yuan, Chun-an FanAbstract:Alkenes can be stereoselectively arylated and vinylated without transition-metal catalyst under mild conditions through an interesting NBS-promoted semipinacol rearrangement and a subsequent unusual NaOH-mediated Grob Fragmentation.
Alain Krief - One of the best experts on this subject based on the ideXlab platform.
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unprecedented dual reactivity of anhydrous potassium hydroxide in cascade cyclopropannelation haller bauer scission Grob Fragmentation reactions
Tetrahedron Letters, 2010Co-Authors: Alain Krief, Adrian KremerAbstract:Abstract We report an unprecedented type of reactivity of ‘anhydrous potassium hydroxide’ (‘APH’) in which it plays, over a large variety of related educts, sequentially the role of base and nucleophile. Some insight into the structure of reactive species as well as comparative reactivity of related reagents prepared by fusion of commercially available potassium hydroxide or by adding stoichiometric amount of water to potassium hydride is provided.
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Stereochemical issues on the Fragmentation of non-enolisable β-heterosubstituted-cyclopentanones with wet and anhydrous potassium hydroxide
Tetrahedron Letters, 2010Co-Authors: Alain Krief, Adrian KremerAbstract:Abstract Tandem Haller–Bauer-scission/Grob-Fragmentation reaction of cyclopentanone bearing a leaving group in β-position involves antiperiplanar arrangements which can be also achieved from epimeric derivatives, probably due to the high flexibility of the five-membered ring. We have observed that epimeric compounds react at different rates if the leaving group is a halogen and leads to very different types of compounds when it is a mesyl group.
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Unprecedented dual reactivity of anhydrous potassium hydroxide in cascade cyclopropannelation/Haller–Bauer-scission/Grob-Fragmentation reactions
Tetrahedron Letters, 2010Co-Authors: Alain Krief, Adrian KremerAbstract:Abstract We report an unprecedented type of reactivity of ‘anhydrous potassium hydroxide’ (‘APH’) in which it plays, over a large variety of related educts, sequentially the role of base and nucleophile. Some insight into the structure of reactive species as well as comparative reactivity of related reagents prepared by fusion of commercially available potassium hydroxide or by adding stoichiometric amount of water to potassium hydride is provided.
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Isomerisation of 2,2-dimethyl dimedone to (d,l) cis-chrysanthemic acid†
Tetrahedron Letters, 2000Co-Authors: Alain Krief, Guillaume Lorvelec, Stephane JeanmartAbstract:Abstract ( d , l ) cis -Chrysanthemic acid has been obtained in four steps from 2,2-dimethyl dimedone which involves Bamford–Stevens olefination and tandem cyclization–Grob Fragmentation reactions.
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Novel enantioselective syntheses of optically active (1R)-cis- and (1R)-trans-chrysanthemic acids.
Tetrahedron: Asymmetry, 1993Co-Authors: Alain Krief, D. Surleraux, Nathalie RopsonAbstract:Abstract Dimethyl dimedone, a non chiral and cheap compound, has been converted to the optically actives 1-(R)- cis - and 1-(R)- trans -chrysanthemic acids possessing high economic value. These processes involve as the key steps (i) a cyclopropanation reaction (ii) a Grob Fragmentation and (iii) a lipase monitored hydrolysis of a prochiral diacetate.
