The Experts below are selected from a list of 120 Experts worldwide ranked by ideXlab platform
Yasuji Yamada - One of the best experts on this subject based on the ideXlab platform.
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Total synthesis of the dolabellane marine diterpenoids, claenone, palominol and dolabellatrienone
Tetrahedron, 2003Co-Authors: Hiroaki Miyaoka, Yutaka Isaji, Hidemichi Mitome, Yasuji YamadaAbstract:Abstract The synthesis of marine dolabellane diterpenoids claenone, palominol and dolabellatrienone was conducted from d -mannitol. In each case, formation of the bicyclo[2.2.1]heptane Derivative by sequential Michael reaction, preparation of the tetrasubstituted Cyclopentane Derivative by retro-aldol reaction and cyclization of sulfone were involved as key steps.
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Total synthesis of marine diterpenoid stolonidiol
Tetrahedron Letters, 2001Co-Authors: Hiroaki Miyaoka, Hidemichi Mitome, Tomohiro Baba, Yasuji YamadaAbstract:Abstract Marine dolabellane diterpenoid stolonidiol was synthesized from l -ascorbic acid. The method for this total synthesis involves formation of the bicyclo[2.2.1]heptane Derivative using a diastereoselective sequential Michael reaction, formation of Cyclopentane Derivative by the retro-aldol reaction and construction of an 11-membered carbocyclic ring through the intramolecular Horner–Wadsworth–Emmons reaction.
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Total Synthesis of Marine Oxylipin Bacillariolides I–III
Tetrahedron, 2000Co-Authors: Hiroaki Miyaoka, Masahide Tamura, Yasuji YamadaAbstract:Abstract Marine oxylipin bacillariolides I–III were synthesized from (R)-malic acid, using diastereoselective one-pot formation of the chiral Cyclopentane Derivative from the anion of allyl phenyl sulfone and chiral epoxymesylate as the key reaction.
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Total synthesis of dolabellane diterpenoid claenone
Tetrahedron Letters, 1998Co-Authors: Hiroaki Miyaoka, Yutaka Isaji, Yasuhiro Kajiwara, Iyo Kunimune, Yasuji YamadaAbstract:Abstract Marine dolabellane diterpenoid claenone ( 1 ) was synthesized from D-mannitol. This synthesis involves the formation of bicyclo[2.2.1]heptane Derivative 4a by sequential Michael reaction, the formation of Cyclopentane Derivative 9 by retro-aldol reaction and the cyclization of sulfone 19 .
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Synthesis of Cyclopentane-containing marine eicosanoid bacillariolide II
Tetrahedron Letters, 1998Co-Authors: Hiroaki Miyaoka, Masahide Tamura, Yasuji YamadaAbstract:Abstract Marine eicosanoid bacillariolide II was synthesized from ( R )-malic acid, involving the diastereoselective one-pot formation of chiral Cyclopentane Derivative 12 from the anion of allyl phenyl sulfone and chiral epoxymesylate 11 as the key step.
Miwako Mori - One of the best experts on this subject based on the ideXlab platform.
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Intramolecular Cyclization of Ene-Imine Using Dibutylzirconocene
Journal of Organic Chemistry, 2004Co-Authors: Muneyoshi Makabe, Yoshihiro Sato, Miwako MoriAbstract:The reaction of ene-imine with Cp2ZrBu2 was carried out. When a crude imine, which was prepared from ene-aldehyde and primary amine in the presence of MgSO4, was treated with Cp2ZrBu2 at room temperature overnight, Cyclopentane Derivative having trans-substituents was obtained in high yield along with a small amount of Cyclopentane Derivative having cis-substituents. Presumably, cis-zirconacycle is a thermodynamic product. Reactions using various ene-imines were carried out. In the case of ene-imine prepared from ene-aldehyde and tBuNH2, only Cyclopentane having cis-substituents was produced. In this reaction, chiral amine was used, and diastereoselective cyclization of ene-imine was carried out. As a result, Cyclopentane Derivative having cis-substituents was obtained in an optically active form after hydrogenolysis of the cyclized compound.
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Zirconium-Mediated Intramolecular Cyclization of Yne-Imine
Synthesis, 2004Co-Authors: Muneyoshi Makabe, Yoshihiro Sato, Miwako MoriAbstract:Successful zirconium-mediated intramolecular cyclization of yne-imine was achieved. When a crude imine, which was prepared from yne-aldehyde and primary amine in the presence of MgSO 4 , was treated with Cp 2 ZrBu 2 at roomtemperature for several hours, a Cyclopentane Derivative was obtained in high yield. The intermediary azazirconacycle was treated with D 3 O + , I 2 or t-BuNC to give the desired deuterated, iodinated or formylated product, respectively, at the vinyl position in good yield. Transmetalation of zirconacycle to CuCl was carried out and then allyl chloride was added to give an allylated compound in good yield. Selective bond fission of a zirconium-nitrogen bond of the azazirconacycle was achieved by treatment of the azazirconacycle with acyl halide to give an N-acylated vinylzirconium compound.
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Enantioselective synthesis of Cyclopentane Derivatives using zirconium-catalyzed asymmetric cyclization
Tetrahedron Letters, 1999Co-Authors: Yousuke Yamaura, Miwako MoriAbstract:Abstract Cyclization of diene 2a using ( S )-(EBTHI)ZrBINOL ( 1 ) (10 mol %) and BuMgCl in THF upon heating gave Cyclopentane Derivative trans - 3a with 99% ee and cis - 3a with 86% ee in 69% and 31 % yields, respectively. In a similar manner, diene 10 gave Cyclopentane Derivative cis - 11 with 94% ee in 81% yield as a sole product.
Akio Yamada - One of the best experts on this subject based on the ideXlab platform.
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transition metal catalyzed asymmetric cycloaddition reactions of a chiral β sulfinyl vinylcyclopropane Derivative asymmetric synthesis of a Cyclopentane Derivative using a chiral sulfinyl functionality as the chiral source
Tetrahedron-asymmetry, 2000Co-Authors: Kunio Hiroi, Akio YamadaAbstract:Abstract Asymmetric synthesis of a Cyclopentane Derivative using a chiral sulfinyl functionality as the chiral source has been successfully executed by a transition metal-catalyzed asymmetric cycloaddition reaction of a chiral (β-sulfinyl)vinylcyclopropane Derivative with acrylonitrile. The effects of the catalysts, ligands, and solvent were examined. The degree of the asymmetric induction and the chemical yield were highly dependent on the catalyst and, especially, the ligand used. A plausible mechanism of the asymmetric induction is proposed.
Hiroaki Miyaoka - One of the best experts on this subject based on the ideXlab platform.
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Total synthesis of the dolabellane marine diterpenoids, claenone, palominol and dolabellatrienone
Tetrahedron, 2003Co-Authors: Hiroaki Miyaoka, Yutaka Isaji, Hidemichi Mitome, Yasuji YamadaAbstract:Abstract The synthesis of marine dolabellane diterpenoids claenone, palominol and dolabellatrienone was conducted from d -mannitol. In each case, formation of the bicyclo[2.2.1]heptane Derivative by sequential Michael reaction, preparation of the tetrasubstituted Cyclopentane Derivative by retro-aldol reaction and cyclization of sulfone were involved as key steps.
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Total synthesis of marine diterpenoid stolonidiol
Tetrahedron Letters, 2001Co-Authors: Hiroaki Miyaoka, Hidemichi Mitome, Tomohiro Baba, Yasuji YamadaAbstract:Abstract Marine dolabellane diterpenoid stolonidiol was synthesized from l -ascorbic acid. The method for this total synthesis involves formation of the bicyclo[2.2.1]heptane Derivative using a diastereoselective sequential Michael reaction, formation of Cyclopentane Derivative by the retro-aldol reaction and construction of an 11-membered carbocyclic ring through the intramolecular Horner–Wadsworth–Emmons reaction.
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Total Synthesis of Marine Oxylipin Bacillariolides I–III
Tetrahedron, 2000Co-Authors: Hiroaki Miyaoka, Masahide Tamura, Yasuji YamadaAbstract:Abstract Marine oxylipin bacillariolides I–III were synthesized from (R)-malic acid, using diastereoselective one-pot formation of the chiral Cyclopentane Derivative from the anion of allyl phenyl sulfone and chiral epoxymesylate as the key reaction.
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Total synthesis of dolabellane diterpenoid claenone
Tetrahedron Letters, 1998Co-Authors: Hiroaki Miyaoka, Yutaka Isaji, Yasuhiro Kajiwara, Iyo Kunimune, Yasuji YamadaAbstract:Abstract Marine dolabellane diterpenoid claenone ( 1 ) was synthesized from D-mannitol. This synthesis involves the formation of bicyclo[2.2.1]heptane Derivative 4a by sequential Michael reaction, the formation of Cyclopentane Derivative 9 by retro-aldol reaction and the cyclization of sulfone 19 .
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Synthesis of Cyclopentane-containing marine eicosanoid bacillariolide II
Tetrahedron Letters, 1998Co-Authors: Hiroaki Miyaoka, Masahide Tamura, Yasuji YamadaAbstract:Abstract Marine eicosanoid bacillariolide II was synthesized from ( R )-malic acid, involving the diastereoselective one-pot formation of chiral Cyclopentane Derivative 12 from the anion of allyl phenyl sulfone and chiral epoxymesylate 11 as the key step.
Kunio Hiroi - One of the best experts on this subject based on the ideXlab platform.
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transition metal catalyzed asymmetric cycloaddition reactions of a chiral β sulfinyl vinylcyclopropane Derivative asymmetric synthesis of a Cyclopentane Derivative using a chiral sulfinyl functionality as the chiral source
Tetrahedron-asymmetry, 2000Co-Authors: Kunio Hiroi, Akio YamadaAbstract:Abstract Asymmetric synthesis of a Cyclopentane Derivative using a chiral sulfinyl functionality as the chiral source has been successfully executed by a transition metal-catalyzed asymmetric cycloaddition reaction of a chiral (β-sulfinyl)vinylcyclopropane Derivative with acrylonitrile. The effects of the catalysts, ligands, and solvent were examined. The degree of the asymmetric induction and the chemical yield were highly dependent on the catalyst and, especially, the ligand used. A plausible mechanism of the asymmetric induction is proposed.
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Transition Metal-catalyzed Asymmetric Vinylcyclopropane-Cyclopentene Rearrangements with Chiral Phosphine Ligands. Dramatic Solvent Effects on Asymmetric Induction
Chemistry Letters, 1992Co-Authors: Kunio Hiroi, Yoshihisa Arinaga, Takashi OginoAbstract:A dramatic solvent effect was observed on the nickel-catalyzed asymmetric rearrangement of a cyclopropane system into an optically active Cyclopentane Derivative with chiral phosphine ligands. The stereochemistry of the product was readily controlled by selecting the catalyst, nickel or palladium, with extremely high enantioselectivity.
