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



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



Journal of Organic Chemistry 71(12): 4364-4373



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.

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Accession: 048328427

Download citation: RISBibTeXText

PMID: 16749763

DOI: 10.1021/jo052435g


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