Dynamic resolution of α-halo chiral esters for the synthesis of 3-substituted piperazin-2-ones
作者:Jung In Jang、Seock Yong Kang、Kyoung Hee Kang、Yong Sun Park
DOI:10.1016/j.tet.2011.06.055
日期:2011.8
Dynamicresolution of α-halo esters derived from five chiral alcohols has been investigated in nucleophilicsubstitution with ethylenediamine nucleophiles. Stereoselective substitution of α-halo esters and following spontaneous cyclization provide a practical protocol for asymmetricsyntheses of 3-substituted piperazin-2-ones up to 94:6 er.
Dynamic Resolution of α-Bromo-α-Alkyl Esters Using N-Methyl Pseudo-ephedrine as a Chiral Auxiliary: Asymmetric Syntheses of α-Amino Acid Derivatives
作者:Sang-kuk Lee、Jiyoun Nam、Yong Sun Park
DOI:10.1055/s-2002-25373
日期:——
esters 1, 4 and 5 are allowed to equilibrate before the addition of nucleophile. This simple epimerization-substitution sequence provides a practical protocol for asymmetric syntheses of α-amino acidderivatives 2, 7 and 8 up to 98:2 enantiomeric ratio.