Enantioselective fluoride ring opening of aziridines enabled by cooperative Lewis acid catalysis
Enantioselective fluoride ring opening of aziridines enabled by cooperative Lewis acid catalysis
复制标题
DOI：
10.1016/j.tet.2013.01.062
复制
发表时间：
2013-07-08
期刊：
影响因子：
2.1
通讯作者：
Doyle, Abigail G.
中科院分区：
文献类型：
--
作者：
Kalow, Julia A.;Doyle, Abigail G.
报道了氮杂环丙烷在潜在氢氟源作用下的对映选择性开环反应。两种Lewis酸(Salen)Co和无手性Ti(IV)助催化剂的组合为反式β-氟胺产品提供了最佳的反应活性和对映体选择性。使用螯合氮杂环丙烷保护基团是至关重要的。无环和环状N-吡啶甲酰胺氮杂环丙烷在高达84%的ee中开环，动力学拆分的k(REL)=6.6。在不使氟胺异构化的情况下，可以容易地去除吡啶甲酰胺基团。初步研究揭示了一种双金属反应机理，其中手性(Salen)Co催化剂提供亲核剂，而Ti(IV)助催化剂激活氮杂环丙烷。(C)2013爱思唯尔有限公司。保留所有权利。
The enantioselective ring opening of aziridines using a latent source of HF is described. A combination of two Lewis acids, (salen)Co and an achiral Ti(IV) cocatalyst, provided optimal reactivity and enantioselectivity for the trans beta-fluoroamine product. The use of a chelating aziridine protecting group was crucial. Acyclic and cyclic meso N-picolinamide aziridines underwent fluoride ring opening in up to 84% ee, and the kinetic resolution of a piperidine-derived aziridine was performed with k(rel)=6.6. The picolinamide group may be readily removed without epimerization of the fluoroamine. Preliminary studies revealed a bimetallic mechanism wherein the chiral (salen)Co catalyst delivers the nucleophile and the Ti(IV) cocatalyst activates the aziridine. (C) 2013 Elsevier Ltd. All rights reserved.