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    Enantioselective Creation of Quaternary Carbon Centers through Addition- Elimination Reaction: Asymmetric Nitroolefination of 3-Substituted 2-Oxindoles
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    Abstract:
    Nitroolefination of 3-substituted 2-oxindoles with nitroenamine (5) afforded the corresponding products having quatemary carbon centers with high ee in good yield.Application of this method to concise syntheses of (-)- esermethole ( 24) and (-)-pseudophrynaminol ( 28) is described.Asymmetric creation of quatemary carbon centers is a matter of infinite importance in organic synthesis.'Nearly ten years ago, we reported high asymmetric induction through addition-elimination process to construct a chiral carbon at the a-position of 6-lactone~,~ and the products were used as chiral building
    Keywords:
    Quaternary carbon
    Carbon fibers
    Asymmetric induction
    A 3-step asymmetric approach toward the optically active chiral cyclohex-2-enones from anisoles has been developed. The crucial asymmetric induction step is an unprecedented catalytic enantioselective isomerization of β,γ-unsaturated cyclohex-3-en-1-ones to the corresponding α,β-unsaturated chiral enones. This new asymmetric transformation was realized by cooperative iminium-base catalysis with an electronically tunable new organic catalyst. The synthetic utility of this methodology is highlighted by the enantioselective total synthesis of (-)-isoacanthodoral.
    Asymmetric induction
    Iminium
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    Mannich reaction
    Aldol reaction
    Hydrocyanation
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    The first catalytic enantioselective route to (R)-(+) Lasiodiplodin is described. Introduction of the asymmetric center was accomplished by the enantioselective addition of dimethyl zinc to an aldehyde, mediated by a tricarbonyl (η6 arene) chromium(0) catalyst.
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    Abstract It is proposed that asymmetric syntheses be divided into enantioselective and diastereoselective syntheses. The enantioselective hydrogenations discussed in the present progress report were catalyzed by Raney nickel that had previously been treated with solutions of optically active compounds. Relationships exist between the enantioselectivity of the catalyst and the structure of the chiral compound used to modify it.
    Raney nickel
    Asymmetric hydrogenation
    Citations (144)
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