Fluorinated Organocatalysts for the Enantioselective Epoxidation of Enals: Molecular Preorganisation by the Fluorine-Iminium Ion Gauche Effect
作者:Eva-Maria Tanzer、Lucie E. Zimmer、W. Bernd Schweizer、Ryan Gilmour
DOI:10.1002/chem.201201316
日期:2012.9.3
The fluorine‐iminium ion gauche effect is triggered upon union of a secondary β‐fluoroamine and an α,β‐unsaturated aldehyde, providing a useful strategy for controlling the molecular topology of intermediates that are central to organocatalytic processes. The β‐fluoroamine (S)‐2‐(fluorodiphenylmethyl)pyrrolidine (1) is an effective catalyst for the enantioselective epoxidation of α,β‐unsaturated aldehydes
当仲β-氟胺和α,β-不饱和醛结合后会触发氟亚胺离子的网状效应,为控制有机催化过程中重要的中间体的分子拓扑提供了有用的策略。β-氟胺(S)-2-(氟二苯基甲基)吡咯烷(1)是α,β-不饱和醛对映选择性环氧化的有效催化剂。结构编辑的过程表明,该催化剂的效率归因于嵌入在β-氟亚胺基序中的(氟二苯基)甲基。1催化具有挑战性的环状α,β-二取代,β,β-二取代和α,β,β-三取代的烯醛继续进行优异的对映体控制(高达98% ee)。