α,β‐Unsaturated Amides as Dipolarophiles: Catalytic Asymmetric
<i>exo</i>
‐Selective 1,3‐Dipolar Cycloaddition with Nitrones
作者:Ming Zhang、Naoya Kumagai、Masakatsu Shibasaki
DOI:10.1002/chem.201702330
日期:2017.9.12
1,3-Dipolar cycloaddition is a commonly exploited method to access 5-membered chemical entities with a variety of peripheral functionalities and their stereochemical arrangements. Nitrones are isolable 1,3-dipoles that exhibit sufficient reactivity toward electron-deficient olefins in the presence of Lewis acids to deliver highly substituted isoxazolidines. Herein we document that α,β-unsaturated amides
1,3-偶极环加成是访问具有多种外围功能及其立体化学排列的5元化学实体的一种常用方法。硝基是可分离的1,3-偶极,在路易斯酸的存在下对缺电子的烯烃表现出足够的反应性,以递送高度取代的异恶唑烷。在本文中,我们记录了在In(OTf)3 /双异羟肟酸催化体系中使用设计的7-氮杂二氢吲哚助剂有效活化了通常被认为在1,3-偶极反应歧管中几乎没有反应性的α,β-不饱和酰胺。广泛的底物范围和从产物中干净地去除7-氮杂二氢吲哚助剂突出了本催化方法的合成用途。