Highly Diastereo- and Enantioselective Additions of Homoenolates to Nitrones Catalyzed by <i>N</i>-Heterocyclic Carbenes
作者:Eric M. Phillips、Troy E. Reynolds、Karl A. Scheidt
DOI:10.1021/ja710521m
日期:2008.2.1
diastereo- and enantioselective addition of N-heterocyclic carbene-generated homoenolates to nitrones is reported. This formal [3 + 3] addition of α,β-unsaturated aldehydes and nitrones generates unusual morpholinone heterocycles which are converted into γ-hydroxy amino esters by addition of methanol to the reaction. The use of a chiral N-heterocyclic carbene (NHC) as the catalyst provides the amino esters
据报道,N-杂环卡宾生成的同烯醇化物对硝酮的非对映选择性和对映选择性加成。α,β-不饱和醛和硝酮的正式 [3 + 3] 加成生成不寻常的吗啉酮杂环,通过向反应中加入甲醇将其转化为 γ-羟基氨基酯。使用手性 N-杂环卡宾 (NHC) 作为催化剂提供了高非对映选择性(高达 20:1 dr)和对映选择性(高达 94%)的氨基酯。该方法适用于具有 β-烷基和 β-芳基取代基的 α,β-不饱和醛。γ-羟基氨基酯可以通过两步程序转化为光学富集的 γ-内酰胺,包括温和还原 NO 键和酸催化酰胺形成。