Asymmetric halogenation of chiral imide enolates. A general approach to the synthesis of enantiomerically pure α-amino acids.
作者:David A Evans、Jon A Ellman、Roberta L Dorow
DOI:10.1016/s0040-4039(00)95305-x
日期:1987.1
The chiral N-acyl oxazolidones 2, as the derived dibutyl boron enolates, have been demonstrated to undergo diastereoselective bromination and subsequent azide displacement to give the α-azido carboximides 4a (5 cases). These adducts may be hydrolyzed under mild conditions to the enantiomerically pure α-azido carboxylic acids 5a.
The asymmetric synthesis of α-amino and α-hydrazino acid derivatives via the stereoselective amination of chiral enolates with azodicarboxylate esters
作者:David A. Evans、Thomas C. Britton、Roberta L. Dorow、Joseph F. Dellaria
DOI:10.1016/s0040-4020(01)86058-0
日期:1988.1
(+)NH2 and (+)NH-NH2 synthons in highly diastereoselective reactions with chiral carboximide-derived enolates has been demonstrated. The lithium enolates derived from 4-substituted N-acyl 2-oxazolidinones were found to react with di-tert-butyl azodicarboxylate (DBAD) to afford the derived 2-hydrazido carboxylic acidderivatives in yields in excess of 90%. The diastereoselectivities of these reactions