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Shuli You - One of the best experts on this subject based on the ideXlab platform.
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iridium catalyzed intramolecular asymmetric allylic alkylation of hydroxyquinolines simultaneous weakening of the aromaticity of two consecutive aromatic rings
Journal of the American Chemical Society, 2018Co-Authors: Zepeng Yang, Ru Jiang, Chao Zheng, Shuli YouAbstract:Intramolecular asymmetric allylic alkylation reactions of 5- and 7-hydroxyquinoline derivatives were realized by a chiral Ir/NHC catalyst. A series of functionalized cyclic enones were afforded in excellent yields (up to 99%) and high enantioselectivity (up to 97% ee). Theoretical computations revealed that the aromaticity of the two consecutive rings of hydroxyquinoline substrates is significantly weakened. A highly efficient formal synthesis of (−)-Gephyrotoxin was accomplished based on this method.
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Iridium-Catalyzed Intramolecular Asymmetric Allylic Alkylation of Hydroxyquinolines: Simultaneous Weakening of the Aromaticity of Two Consecutive Aromatic Rings
2018Co-Authors: Zepeng Yang, Ru Jiang, Chao Zheng, Shuli YouAbstract:Intramolecular asymmetric allylic alkylation reactions of 5- and 7-hydroxyquinoline derivatives were realized by a chiral Ir/NHC catalyst. A series of functionalized cyclic enones were afforded in excellent yields (up to 99%) and high enantioselectivity (up to 97% ee). Theoretical computations revealed that the aromaticity of the two consecutive rings of hydroxyquinoline substrates is significantly weakened. A highly efficient formal synthesis of (−)-Gephyrotoxin was accomplished based on this method
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iridium catalyzed intramolecular asymmetric allylic dearomatization reaction of pyridines pyrazines quinolines and isoquinolines
Journal of the American Chemical Society, 2015Co-Authors: Zepeng Yang, Wen Shao, Shuli YouAbstract:The first Ir-catalyzed intramolecular asymmetric allylic dearomatization reaction of pyridines, pyrazines, quinolines, and isoquinolines has been developed. Enabled by in situ formed chiral Ir-catalyst, the dearomatized products were isolated in high levels of yield (up to 99% yield) and enantioselectivity (up to 99% ee). It is worth noting that the Me-THQphos ligand is much more efficient than other tested ligands for the dearomatization of pyrazines and certain quinolines. Mechanistic studies of the dearomatization reaction were carried out, and the results suggest the feasibility of an alternative process which features the formation of a quinolinium as the key intermediate. The mechanistic findings render this reaction a yet unknown type in the chemistry of Reissert-type reactions. In addition, the utility of this method was showcased by a large-scale reaction and formal synthesis of (+)-Gephyrotoxin.
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Iridium-Catalyzed Intramolecular Asymmetric Allylic Dearomatization Reaction of Pyridines, Pyrazines, Quinolines, and Isoquinolines
2015Co-Authors: Zepeng Yang, Wen Shao, Shuli YouAbstract:The first Ir-catalyzed intramolecular asymmetric allylic dearomatization reaction of pyridines, pyrazines, quinolines, and isoquinolines has been developed. Enabled by in situ formed chiral Ir-catalyst, the dearomatized products were isolated in high levels of yield (up to 99% yield) and enantioselectivity (up to 99% ee). It is worth noting that the Me-THQphos ligand is much more efficient than other tested ligands for the dearomatization of pyrazines and certain quinolines. Mechanistic studies of the dearomatization reaction were carried out, and the results suggest the feasibility of an alternative process which features the formation of a quinolinium as the key intermediate. The mechanistic findings render this reaction a yet unknown type in the chemistry of Reissert-type reactions. In addition, the utility of this method was showcased by a large-scale reaction and formal synthesis of (+)-Gephyrotoxin
Zepeng Yang - One of the best experts on this subject based on the ideXlab platform.
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iridium catalyzed intramolecular asymmetric allylic alkylation of hydroxyquinolines simultaneous weakening of the aromaticity of two consecutive aromatic rings
Journal of the American Chemical Society, 2018Co-Authors: Zepeng Yang, Ru Jiang, Chao Zheng, Shuli YouAbstract:Intramolecular asymmetric allylic alkylation reactions of 5- and 7-hydroxyquinoline derivatives were realized by a chiral Ir/NHC catalyst. A series of functionalized cyclic enones were afforded in excellent yields (up to 99%) and high enantioselectivity (up to 97% ee). Theoretical computations revealed that the aromaticity of the two consecutive rings of hydroxyquinoline substrates is significantly weakened. A highly efficient formal synthesis of (−)-Gephyrotoxin was accomplished based on this method.
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Iridium-Catalyzed Intramolecular Asymmetric Allylic Alkylation of Hydroxyquinolines: Simultaneous Weakening of the Aromaticity of Two Consecutive Aromatic Rings
2018Co-Authors: Zepeng Yang, Ru Jiang, Chao Zheng, Shuli YouAbstract:Intramolecular asymmetric allylic alkylation reactions of 5- and 7-hydroxyquinoline derivatives were realized by a chiral Ir/NHC catalyst. A series of functionalized cyclic enones were afforded in excellent yields (up to 99%) and high enantioselectivity (up to 97% ee). Theoretical computations revealed that the aromaticity of the two consecutive rings of hydroxyquinoline substrates is significantly weakened. A highly efficient formal synthesis of (−)-Gephyrotoxin was accomplished based on this method
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iridium catalyzed intramolecular asymmetric allylic dearomatization reaction of pyridines pyrazines quinolines and isoquinolines
Journal of the American Chemical Society, 2015Co-Authors: Zepeng Yang, Wen Shao, Shuli YouAbstract:The first Ir-catalyzed intramolecular asymmetric allylic dearomatization reaction of pyridines, pyrazines, quinolines, and isoquinolines has been developed. Enabled by in situ formed chiral Ir-catalyst, the dearomatized products were isolated in high levels of yield (up to 99% yield) and enantioselectivity (up to 99% ee). It is worth noting that the Me-THQphos ligand is much more efficient than other tested ligands for the dearomatization of pyrazines and certain quinolines. Mechanistic studies of the dearomatization reaction were carried out, and the results suggest the feasibility of an alternative process which features the formation of a quinolinium as the key intermediate. The mechanistic findings render this reaction a yet unknown type in the chemistry of Reissert-type reactions. In addition, the utility of this method was showcased by a large-scale reaction and formal synthesis of (+)-Gephyrotoxin.
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Iridium-Catalyzed Intramolecular Asymmetric Allylic Dearomatization Reaction of Pyridines, Pyrazines, Quinolines, and Isoquinolines
2015Co-Authors: Zepeng Yang, Wen Shao, Shuli YouAbstract:The first Ir-catalyzed intramolecular asymmetric allylic dearomatization reaction of pyridines, pyrazines, quinolines, and isoquinolines has been developed. Enabled by in situ formed chiral Ir-catalyst, the dearomatized products were isolated in high levels of yield (up to 99% yield) and enantioselectivity (up to 99% ee). It is worth noting that the Me-THQphos ligand is much more efficient than other tested ligands for the dearomatization of pyrazines and certain quinolines. Mechanistic studies of the dearomatization reaction were carried out, and the results suggest the feasibility of an alternative process which features the formation of a quinolinium as the key intermediate. The mechanistic findings render this reaction a yet unknown type in the chemistry of Reissert-type reactions. In addition, the utility of this method was showcased by a large-scale reaction and formal synthesis of (+)-Gephyrotoxin
Gérard Lhommet - One of the best experts on this subject based on the ideXlab platform.
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Formal Total Synthesis of (+)-Gephyrotoxin
The Journal of organic chemistry, 2008Co-Authors: Marco Santarem, Corinne Vanucci-bacqué, Gérard LhommetAbstract:An efficient formal total synthesis of (+)-Gephyrotoxin is described. The key step of our strategy relies on the diastereoselective reduction of a chiral pyrrolidine β-enamino ester obtained by condensation of (S)-phenylglycinol on a protected 8-hydroxy-3,6-dioxooctanoate.
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formal total synthesis of Gephyrotoxin
Journal of Organic Chemistry, 2008Co-Authors: Marco Santarem, Corinne Vanuccibacque, Gérard LhommetAbstract:An efficient formal total synthesis of (+)-Gephyrotoxin is described. The key step of our strategy relies on the diastereoselective reduction of a chiral pyrrolidine β-enamino ester obtained by condensation of (S)-phenylglycinol on a protected 8-hydroxy-3,6-dioxooctanoate.
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enantioselective synthesis of 5r 9r 5 propyl octahydroindolizine Gephyrotoxin 167b
Tetrahedron-asymmetry, 1992Co-Authors: A. Fleurant, Jean-pierre Célérier, Gérard LhommetAbstract:Abstract A versatile and practical synthesis of the dendrobatid alkaloid 167B is described using a chiral amino acid as starting material.
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Enantioselective synthesis of (5R,9R)-5-propyl-octahydroindolizine [(−)-Gephyrotoxin 167B]
Tetrahedron: Asymmetry, 1992Co-Authors: A. Fleurant, Jean-pierre Célérier, Gérard LhommetAbstract:Abstract A versatile and practical synthesis of the dendrobatid alkaloid 167B is described using a chiral amino acid as starting material.
Aleksey I. Gerasyuto - One of the best experts on this subject based on the ideXlab platform.
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Reactions of Vinylogous Amides Tethered with a, b-Unsaturated Iminiums. A Formal Total Synthesis of (+)-Gephyrotoxin
2015Co-Authors: Lin-li Wei, Richard P. Hsung, Heather M. Sklenicka, Aleksey I. Gerasyuto, Tbscl ImidAbstract:To a round bottom flask is added 0.178 mol propargyl alcohol, and 350 mL THF. The reaction is cooled to 0 oC followed by addition of 0.196 mol TBSCl, 0.2 mol imidazole, and 0.017 mol DMAP. The reaction is stirred and allowed to come to room temperature. Upon completion by TLC the solvent is removed and column chromatography gave 91 % yield of the protected alcohol. The protected alcohol (80.7 mmol) was dissolved in 225 mL THF and HMPA (1.44 mL) as well as 3 mg triphenylmethanol were added. This solution was cooled to –40 oC (dry ice/acetone) and 80.7 mmol n-BuLi (2.18 M in hexanes) is added dropwise. After stirring for 30 minutes the reaction is warmed to room temperature. 1,3-dibromopropane (for hexenol) or 1,4-dibromobutane (for heptenol) (161.4 mmol) is then filtered through silica and added to the reaction mixture. The reaction was allowed to stir for 2 days at room temperature. Quenching of the reaction was done with dropwise addition of water. THF was removed under reduced pressure, and extracted from ether/water. Removal of solvents from the organic layer followed by distillation of the excess dibromopropane gave 53 % yield of the alkyne. The alkyne is then dissolved in 45 mL DMSO and to that is added 0.0639 mol sodium azide. The reaction is placed under nitrogen and allowed to stir at room temperature for 18 hours. An equal volume of water was then added followed by extraction with ether, washing of the organic layer with brine, and drying over sodium sulfate. Solvent was removed from the organic layer and flash column chromatography was used to further purify the compound. The azide (6.4 mmol) was then dissolved in 20 mL THF. This solution was transferred by cannula to 60 mL THF containing 57.6 mmol lithium aluminum hydride. Refluxing of the solution continued for 20 hours. The reaction mixture was cooled to 0 oC and saturated sodium sulfate was slowly added unti
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A Novel and Highly Stereoselective Intramolecular Formal [3+3] Cycloaddition Reaction of Vinylogous Amides Tethered with α,β-Unsaturated Aldehydes: A Formal Total Synthesis of (+)-Gephyrotoxin.
Angewandte Chemie (International ed. in English), 2001Co-Authors: Lin-li Wei, Richard P. Hsung, Heather M. Sklenicka, Aleksey I. GerasyutoAbstract:Complex piperidinyl heterocycles (for example, 2) were accessed by using a novel intramolecular formal [3+3] cycloaddition reaction of vinylogous amides tethered with enals (for example, 1). This method has been applied to a formal total synthesis of (+)-Gephyrotoxin (3).
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Highly Stereoselective Intramolecular Formal (3 + 3) Cycloaddition Reactions of Vinylogous Amides Tethered with α , β β -Unsaturated Iminiums. A Formal Total Synthesis of (+)-Gephyrotoxin
2001Co-Authors: Lin-li Wei, Heather M. Sklenicka, Aleksey I. Gerasyuto, Richard P. HsungAbstract:To a round bottom flask is added 0.178 mol propargyl alcohol, and 350 mL THF. The reaction is cooled to 0 C followed by addition of 0.196 mol TBSCl, 0.2 mol imidazole, and 0.017 mol DMAP. The reaction is stirred and allowed to come to room temperature. Upon completion by TLC the solvent is removed and column chromatography gave 91% yield of the protected alcohol. The protected alcohol (80.7 mmol) was dissolved in 225 mL THF and HMPA (1.44 mL) as well as 3 mg triphenylmethanol were added. This solution was cooled to –40 C (dry ice/acetone) and 80.7 mmol n-BuLi (2.18 M in hexanes) is added dropwise. After stirring for 30 minutes the reaction is warmed to room temperature. 1,3-dibromopropane (for hexenol) or 1,4dibromobutane (for heptenol) (161.4 mmol) is then filtered through silica and added to the reaction mixture. The reaction was allowed to stir for 2 days at room temperature. Quenching of the reaction was done with dropwise addition of water. THF was removed under reduced pressure, and extracted from ether/water. Removal of solvents from the organic layer followed by distillation of the excess dibromopropane gave 53% yield of the alkyne. The alkyne is then dissolved in 45 mL DMSO and to that is added 0.0639 mol sodium azide. The reaction is placed under nitrogen and allowed to stir at room temperature for 18 hours. An equal volume of water was then added followed by extraction with ether, washing of the organic layer with brine, and drying over sodium sulfate. Solvent was removed from the organic layer and flash column chromatography was used to further purify the compound. The azide (6.4 mmol) was then dissolved in 20 mL THF. This solution was transferred by cannula to 60 mL THF containing 57.6 mmol lithium aluminum hydride. Refluxing of the solution continued for 20 hours. The reaction mixture was cooled to 0 C and saturated sodium sulfate was slowly added until CH2OH TBSCl, imid
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highly stereoselective intramolecular formal 3 3 cycloaddition reactions of vinylogous amides tethered with α β β unsaturated iminiums a formal total synthesis of Gephyrotoxin
2001Co-Authors: Lin-li Wei, Heather M. Sklenicka, Aleksey I. Gerasyuto, Richard P. HsungAbstract:To a round bottom flask is added 0.178 mol propargyl alcohol, and 350 mL THF. The reaction is cooled to 0 C followed by addition of 0.196 mol TBSCl, 0.2 mol imidazole, and 0.017 mol DMAP. The reaction is stirred and allowed to come to room temperature. Upon completion by TLC the solvent is removed and column chromatography gave 91% yield of the protected alcohol. The protected alcohol (80.7 mmol) was dissolved in 225 mL THF and HMPA (1.44 mL) as well as 3 mg triphenylmethanol were added. This solution was cooled to –40 C (dry ice/acetone) and 80.7 mmol n-BuLi (2.18 M in hexanes) is added dropwise. After stirring for 30 minutes the reaction is warmed to room temperature. 1,3-dibromopropane (for hexenol) or 1,4dibromobutane (for heptenol) (161.4 mmol) is then filtered through silica and added to the reaction mixture. The reaction was allowed to stir for 2 days at room temperature. Quenching of the reaction was done with dropwise addition of water. THF was removed under reduced pressure, and extracted from ether/water. Removal of solvents from the organic layer followed by distillation of the excess dibromopropane gave 53% yield of the alkyne. The alkyne is then dissolved in 45 mL DMSO and to that is added 0.0639 mol sodium azide. The reaction is placed under nitrogen and allowed to stir at room temperature for 18 hours. An equal volume of water was then added followed by extraction with ether, washing of the organic layer with brine, and drying over sodium sulfate. Solvent was removed from the organic layer and flash column chromatography was used to further purify the compound. The azide (6.4 mmol) was then dissolved in 20 mL THF. This solution was transferred by cannula to 60 mL THF containing 57.6 mmol lithium aluminum hydride. Refluxing of the solution continued for 20 hours. The reaction mixture was cooled to 0 C and saturated sodium sulfate was slowly added until CH2OH TBSCl, imid
Noritaka Chida - One of the best experts on this subject based on the ideXlab platform.
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total syntheses of Gephyrotoxin and perhydroGephyrotoxin
ChemInform, 2015Co-Authors: Kenji Shirokane, Takaaki Sato, Makoto Yoritate, Nobuaki Takayama, Yuya Tanaka, Noritaka ChidaAbstract:The total syntheses of title compounds Gephyrotoxin (I) and perhydroGephyrotoxin (II) are accomplished by taking advantage of an N-methoxy group as a reactivity control element.
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Total Syntheses of (.+-.)-Gephyrotoxin and (.+-.)-PerhydroGephyrotoxin.
ChemInform, 2015Co-Authors: Kenji Shirokane, Takaaki Sato, Makoto Yoritate, Nobuaki Takayama, Yuya Tanaka, Noritaka ChidaAbstract:The total syntheses of title compounds Gephyrotoxin (I) and perhydroGephyrotoxin (II) are accomplished by taking advantage of an N-methoxy group as a reactivity control element.
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total syntheses of Gephyrotoxin and perhydroGephyrotoxin
Bulletin of the Chemical Society of Japan, 2015Co-Authors: Kenji Shirokane, Takaaki Sato, Makoto Yoritate, Nobuaki Takayama, Yuya Tanaka, Noritaka ChidaAbstract:This article describes the full details of our total syntheses of Gephyrotoxin and perhydroGephyrotoxin. Our central strategy toward the total synthesis is based on the use of an N-methoxy group as...
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total synthesis of Gephyrotoxin by amide selective reductive nucleophilic addition
ChemInform, 2014Co-Authors: Kenji Shirokane, Takaaki Sato, Makoto Yoritate, Takamasa Wada, Ryo Minamikawa, Nobuaki Takayama, Noritaka ChidaAbstract:Efficient reaction conditions are established to couple N-substituted Weinreb amides with a variety of carbon nucleophiles using Schwartz′s reagent in the presence of Sc(OTf)3 as the catalyst.
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Total Synthesis of (.+-.)-Gephyrotoxin by Amide-Selective Reductive Nucleophilic Addition.
ChemInform, 2014Co-Authors: Kenji Shirokane, Takaaki Sato, Makoto Yoritate, Takamasa Wada, Ryo Minamikawa, Nobuaki Takayama, Noritaka ChidaAbstract:Efficient reaction conditions are established to couple N-substituted Weinreb amides with a variety of carbon nucleophiles using Schwartz′s reagent in the presence of Sc(OTf)3 as the catalyst.