Enantioselective fluoride ring opening of aziridines enabled by cooperative Lewis acid catalysis

TETRAHEDRON

卷:69

Article

Kalow, Julia A.¹  Doyle, Abigail G.¹ 

[1] Princeton Univ, Dept Chem, Princeton, NJ 08544 USA

关键词: Asymmetric catalysis;    Fluorination;    Aziridine opening;    Cooperative catalysis;    beta-Fluoroamine;   

DOI  :  10.1016/j.tet.2013.01.062

来源: Elsevier

【 摘 要 】

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.

【 授权许可】

Free