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    Asymmetric synthesis of alpha,alpha-disubstituted alpha-amino acids by diastereoselective alkylation of camphor-based tricyclic iminolactone.

    Authors
    Xu PF, Li S, Lu TJ, et al. 
    Institution

    State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, PRC.

    Source
    J Org Chem 2006 Jun 9; 71(12) :4364-73.
    Abstract

    A novel and convenient route for the preparation of chiral tricyclic iminolactones 9 and 10 from camphorquinone has been developed. Alkylation of iminolactones 9 and 10 provided iminolactones 16 and 17 in high yields which were, in turn, alkylated again to afford the alpha,alpha-disubstituted products in good yields (70-90%) and excellent diastereoselectivities (>98%). Hydrolysis of the alkylated iminolactones furnished the desired alpha,alpha-disubstituted alpha-amino acids in good yields and high enantiomeric excesses with good recovery yields of the chiral auxiliary 12 and 13. The extremely high endo-face selectivity for alkylation is discussed using semiempirical (MOPAC 93) calculations.

    Mesh
    Alkylation
    Amino Acids
    Camphor
    Heterocyclic Compounds, 3-Ring
    Imines
    Lactones
    Models, Molecular
    Stereoisomerism
    Language

    eng

    Pub Type(s)
    Journal Article Research Support, Non-U.S. Gov't
    PubMed ID

    16749763

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