Memory of chirality trapping of low inversion barrier 1,4-benzodiazepin-2-one enolates
作者:Paul R. Carlier、Polo C.-H. Lam、Joseph C. DeGuzman、Hongwu Zhao
DOI:10.1016/j.tetasy.2005.08.017
日期:2005.9
We have previously demonstrated that chiral, enantiopure 3-substituted 1,4-benzodiazepin-2-ones undergo retentive deprotonation/trapping at −78 °C, if the N1-substituent is sufficiently large (e.g., i-Pr). Stereocontrol in this reaction is attributed to the formation of an enantiopure, conformationally chiral enolate; at −78 °C a large N1 substituent (e.g., i-Pr) is needed to impart a sufficient barrier
先前我们已经证明,如果N1-取代基足够大(例如,i -Pr),则手性,对映体纯的3-取代的1,4-苯并二氮杂-2-酮会在-78°C下发生保持性去质子化/捕获。该反应中的立体控制归因于对映纯的,构象性的手性烯醇盐的形成。在-78°C下,需要一个大的N1取代基(例如i- Pr)来赋予烯醇外消旋作用足够的屏障。在本文中,我们报告了在低反型势垒1,4-苯并二氮杂-2-酮具有较小N1取代基的去质子化/烷基化中实现高对映体过量的策略。