1
   H NMR nOe spectroscopic studies reveal that 
 conformational control in the enolates of 
 N-acyl-5,5-dimethyl-4-iso-propyloxazolidin-2-ones ensures 
 that the stereodirecting effect of its 4-iso-propyl-5,5-dimethyl 
 functional group affords superior levels of facial selectivity normally 
 associated with enolates derived from 
 N-acyl-4-tert-butyloxazolidin-2-ones.
                                    1 H NMR nOe 光谱研究表明,N-酰基-5,5-二甲基-4-异丙基
恶唑啉-2-酮烯醇盐的构象控制确保了其 4-异丙基-5,5-二甲基官能团的立体定向效应,从而提供了通常与 N-酰基-4-叔丁基
恶唑啉-2-酮烯醇盐相关的卓越的面部选择性。