The Experts below are selected from a list of 3180 Experts worldwide ranked by ideXlab platform
Mei-hua Shen - One of the best experts on this subject based on the ideXlab platform.
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stereoselective construction of bridged trans aza bicyclo 7 6 3 2 1 alkenyl imines through ring expansion aza cope Rearrangement
Organic Letters, 2015Co-Authors: Mei-hua Shen, Chuhan Sun, Huadong XuaAbstract:A highly stereoselective method for efficient synthesis of unprecedented bridged bicyclo[7/6,3/2,1]alkenyl amidines is described using cyclic N-allyl-aminoalkyne as a substrate. A ketenimine formation/cyclization/Aza-Cope Rearrangement cascade proceeds either with or without the aid of external DIPEA depending on substrate basicity. Fused bicycloamidines are also obtained via the same protocol using different N-allyl cyclic aminoalkynes.
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Stereoselective Construction of Bridged trans-aza-Bicyclo[7/6,3/2,1]alkenyl Imines through Ring Expansion Aza-Cope Rearrangement
2015Co-Authors: Mei-hua Shen, Chuhan SunAbstract:A highly stereoselective method for efficient synthesis of unprecedented bridged bicyclo[7/6,3/2,1]alkenyl amidines is described using cyclic N-allyl-aminoalkyne as a substrate. A ketenimine formation/cyclization/Aza-Cope Rearrangement cascade proceeds either with or without the aid of external DIPEA depending on substrate basicity. Fused bicycloamidines are also obtained via the same protocol using different N-allyl cyclic aminoalkynes
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ring strain driven catalytic carbene formation cyclopropanation aza cope Rearrangement cascade a facile entry to fused dihydroazepines from 1 3 dienyltriazoles
Synthesis, 2014Co-Authors: Hao Zhou, Zhihong Jia, Mei-hua ShenAbstract:A practical method for a facile entry to structurally unique ring-fused dihydroazepine has been developed using 1-sulfonyl-1,3-dienyltriazole as starting materials. Driven by ring strain release of cyclopropyl group, a rhodium-catalyzed α-imino carbenoid formation–cyclopropanation–Aza-Cope Rearrangement cascade takes place efficiently in a single operation. Substitution effects on yield and diastereoselectivity are also explored.
Chun-jiang Wang - One of the best experts on this subject based on the ideXlab platform.
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catalytic asymmetric synthesis of quaternary trifluoromethyl α to e amino acid derivatives via umpolung allylation 2 aza cope Rearrangement
Chemical Science, 2020Co-Authors: Xishang Sun, Liang Wei, Hai-yan Tao, Chun-jiang Wang, Xingheng WangAbstract:In this study, we developed an efficient Ir-catalyzed cascade umpolung allylation/2-Aza-Cope Rearrangement of tertiary α-trifluoromethyl α-amino acid derivatives for the preparation of a variety of quaternary α-trifluoromethyl α-amino acids in high yields with excellent enantioselectivities. The umpolung reactivity empowered by the activation of the key isatin-ketoimine moiety obviates the intractable enantioselectivity control in Pd-catalyzed asymmetric linear α-allylation. In combination with quasi parallel kinetic resolution or kinetic resolution, the generality of this method is further demonstrated by the first preparation of enantioenriched quaternary trifluoromethyl β-, γ-, δ- and e-amino acid derivatives.
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catalytic asymmetric synthesis of α trifluoromethyl homoallylic amines via umpolung allylation 2 aza cope Rearrangement stereoselectivity and mechanistic insight
Organic Letters, 2019Co-Authors: Limin Shi, Hai-yan Tao, Chun-jiang Wang, Xishang Sun, Chong Shen, Zuofei WangAbstract:An unprecedented Ir-catalyzed asymmetric cascade umpolung allylation/2-Aza-Cope Rearrangement of trifluoroethylisatin ketimines has been realized. The current method provides a facile access to biologically important α-trifluoromethyl-containing homoallylic amines in high yields with excellent enantioselectivity. Notably, umpolung reactivity of trifluoroethylisatin ketimine was discovered for the first time. Mechanism studies revealed the key intermediates in the initial umpolung allylation and the stereospecific chirality transfer in the subsequent 2-Aza-Cope Rearrangement.
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synergistic catalysis for cascade allylation and 2 aza cope Rearrangement of azomethine ylides
Nature Communications, 2019Co-Authors: Liang Wei, Qiao Zhu, Lu Xiao, Hai-yan Tao, Chun-jiang WangAbstract:The efficient construction of enantiomerically enriched molecules from simple starting materials via catalytic asymmetric synthesis strategies is a key challenge in synthetic chemistry. Metallated azomethine ylides are commonly-used synthons for the preparation of N-heterocycles and α-amino acids. Remarkably, to date, the utilization of azomethine ylides for the facile access to chiral amines has proven elusive. Here, we report that a synergistic Cu/Ir-catalytic system combined with careful tuning of the steric congestion can be used to convert aldimine esters to a variety of chiral homoallylic amines via a cascade allylation/2-Aza-Cope Rearrangement. The elucidation of the distinct effects of each stereogenic center of the allylation intermediates on the stereochemical outcome and chirality transfer in the Rearrangement further guided the selection of catalysts combination.
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Synergistic catalysis for cascade allylation and 2-Aza-Cope Rearrangement of azomethine ylides
Nature Publishing Group, 2019Co-Authors: Liang Wei, Qiao Zhu, Lu Xiao, Hai-yan Tao, Chun-jiang WangAbstract:Metallated azomethine ylides are commonly used for the construction of N-heterocycles and α-amino acids. Here, the authors report a synergistic Cu/Ir-catalytic system that converts aldimine esters to a variety of chiral homoallylic amines via a cascade allylation/2-Aza-Cope Rearrangement
Huadong Xua - One of the best experts on this subject based on the ideXlab platform.
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stereoselective construction of bridged trans aza bicyclo 7 6 3 2 1 alkenyl imines through ring expansion aza cope Rearrangement
Organic Letters, 2015Co-Authors: Mei-hua Shen, Chuhan Sun, Huadong XuaAbstract:A highly stereoselective method for efficient synthesis of unprecedented bridged bicyclo[7/6,3/2,1]alkenyl amidines is described using cyclic N-allyl-aminoalkyne as a substrate. A ketenimine formation/cyclization/Aza-Cope Rearrangement cascade proceeds either with or without the aid of external DIPEA depending on substrate basicity. Fused bicycloamidines are also obtained via the same protocol using different N-allyl cyclic aminoalkynes.
Chuhan Sun - One of the best experts on this subject based on the ideXlab platform.
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stereoselective construction of bridged trans aza bicyclo 7 6 3 2 1 alkenyl imines through ring expansion aza cope Rearrangement
Organic Letters, 2015Co-Authors: Mei-hua Shen, Chuhan Sun, Huadong XuaAbstract:A highly stereoselective method for efficient synthesis of unprecedented bridged bicyclo[7/6,3/2,1]alkenyl amidines is described using cyclic N-allyl-aminoalkyne as a substrate. A ketenimine formation/cyclization/Aza-Cope Rearrangement cascade proceeds either with or without the aid of external DIPEA depending on substrate basicity. Fused bicycloamidines are also obtained via the same protocol using different N-allyl cyclic aminoalkynes.
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Stereoselective Construction of Bridged trans-aza-Bicyclo[7/6,3/2,1]alkenyl Imines through Ring Expansion Aza-Cope Rearrangement
2015Co-Authors: Mei-hua Shen, Chuhan SunAbstract:A highly stereoselective method for efficient synthesis of unprecedented bridged bicyclo[7/6,3/2,1]alkenyl amidines is described using cyclic N-allyl-aminoalkyne as a substrate. A ketenimine formation/cyclization/Aza-Cope Rearrangement cascade proceeds either with or without the aid of external DIPEA depending on substrate basicity. Fused bicycloamidines are also obtained via the same protocol using different N-allyl cyclic aminoalkynes
Matthew J. Sharp - One of the best experts on this subject based on the ideXlab platform.
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aza cope Rearrangement mannich cyclizations for the formation of complex tricyclic amines stereocontrolled total synthesis of gelsemine
Journal of the American Chemical Society, 2005Co-Authors: William G. Earley, Larry E. Overman, Jon E. Jacobsen, Andrew Madin, David W. Old, Christopher J Odonnell, Patrick G Meier, Matthew J. SharpAbstract:A detailed examination of the use of Aza-Cope Rearrangement–Mannich cyclization sequences for assembling the azatricyclo[4.4.0.0 2,8 ]decane core of gelsemine is described. Iminium ions and Nacyloxyiminium ions derived from endo-oriented 1-methoxy- or 1-hydroxybicyclo[2.2.2]oct-5enylamines do not undergo the first step of this sequence, cationic Aza-Cope Rearrangement to form cis-hydroisoquinolinium ions. However, the analogous base-promoted oxy-Aza-Cope Rearrangement does take place to form cis-hydroisoquinolones containing functionality that allows iminium ions or N-acyloxyiminium ions to be generated regioselectively in a subsequent step. Mannich cyclization of cis-hydroisoquinolones prepared in this way efficiently assembles the azatricyclo[4.4.0.0 2,8 ] decane unit of gelsemine. Using a sequential base-promoted oxy-Aza-Cope Rearrangement/Mannich cyclization sequence, gram quantities of azatricyclo[4.4.0.0 2,8 ]decanone 18, a central intermediate in our total of (±)-gelsemine, was prepared from 3-methylanisole in 12 steps and 16% overall yield.
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total synthesis of gelsemine
Angewandte Chemie, 1999Co-Authors: Andrew Madin, David W. Old, Christopher J Odonnell, Matthew J. SharpAbstract:Acomplexmolecularreorganization (1→2), a sequential anionic Aza-Cope Rearrangement and Mannich cyclization, and an unprecedented intramolecular Heck reaction of the tetrasubstituted double bond of a vinylogous carbamate are key steps in a new total synthesis of (±)-gelsemine (3). MOM=methoxymethyl, DBU=1,8-diazabicyclo[5.4.0]undec-7-ene.