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|標題:||Asymmetric synthesis of alpha,alpha-disubstituted alpha-amino acids by diastereoselective alkylation of camphor-based tricyclic iminolactone||作者:||Xu, P.F.
|關鍵字:||chiral glycine equivalent;quantum-chemical am1;stereoselective-synthesis;3,6-dihydro-2h-1,4-oxazin-2-one structure;radical cyclizations;diels-alder;part 1;derivatives;complexes;template||Project:||Journal of Organic Chemistry||期刊/報告no：:||Journal of Organic Chemistry, Volume 71, Issue 12, Page(s) 4364-4373.||摘要:||
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.
|Appears in Collections:||化學系所|
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