Asymmetric Electrophilic Amination of Various Carbon Nucleophiles with Enantiomerically Pure Chiral <i>N</i>-H Oxaziridines Derived from Camphor and Fenchone
作者:Philip C. Bulman Page、Corinne Limousin、Victor L. Murrell
DOI:10.1021/jo020306j
日期:2002.11.1
The first two stableenantiomericallypure chiral N-H oxaziridines, derivedfrom camphor and fenchone, are shown to act as electrophilic sources of nitrogen upon reaction with various carbon nucleophiles. Nitrogen is transferred, together with the camphor/fenchone unit, when deprotonated esters, malonates, and nitriles are used as nucleophiles. One of the ester or nitrile units in the substrate usually
Double chiral induction in ul-selective Michael additions of metal enolates of N-bornylideneglycinates to (E)-4,5-dioxy-2-pentenoates. Exclusive ul,lk-1,2-chiral induction leading to l,u-Michael adducts
ul-Selective Michael additions of metal enolates of ethyl N-[(1R,4R)-bornylidene]glycinate to optically pure (E)-4,5-dioxy-2-pentenoates, such as ethyl (E)-3-(2,2-dimethyl-1,3-dioxolan-4-yl)propenoate, ethyl (E)-3-(1,3-dioxolan-4-yl)propenoate, and ethyl (E)-4,5-diacetoxy-2-pentenoate, proceed through ul,lk-1,2-induction to provide pure enantiomers of 4-substituted 2-oxopyrrolidine-5-carboxylates as single diastereomers. Exclusive ul,lk-1,2-induction is achieved by use of the racemic enolates. Origin of such high stereocontrol is discussed by Kozikowski's antiperiplanar transition model.