State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
Nat Commun. 2011;2:211. doi: 10.1038/ncomms1214.
Iminium catalysis, involving the transformation of iminium ions to enamines, has been extensively studied in the context of a number of organic processes. However, the reverse of this process involving conversion of enamines to iminium species has not been realized. Here, we describe a new transformation-'oxidative enamine catalysis'-in which direct oxidation of an enamine occurs to generate an iminium species. We show that the use of o-iodoxybenzoic acid as an oxidant in the presence of a secondary amine catalyst serves as effective system for promoting rapid conversion of enamines to iminium ions. The preparative power of this process has been demonstrated in the context of direct asymmetric β-functionalization of simple aldehydes. Moreover, a variety of enantioselective cascade transformations, including triple and quadruple cascades, have been developed for the 'one-pot' synthesis of versatile chiral building blocks and structural frameworks starting with simple aldehydes.
亚胺催化，涉及亚胺离子向烯胺的转化，在许多有机过程中得到了广泛的研究。然而，这个过程的逆反应，即烯胺向亚胺物种的转化，尚未实现。在这里，我们描述了一种新的转化——“氧化烯胺催化”，其中直接氧化烯胺生成亚胺物种。我们表明，在二级胺催化剂存在下使用邻碘代苯甲酸作为氧化剂，是促进烯胺快速转化为亚胺离子的有效体系。该过程的制备能力已在简单醛的直接不对称β-官能化背景下得到证明。此外，还开发了多种对映选择性级联转化，包括三重和四重级联转化，用于从简单醛开始，一锅法合成多功能手性砌块和结构框架。
