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 enantioselectiveepoxidation of α,β‐unsaturated aldehydes
Highly enantioenriched products have been prepared in good yields from racemic enal starting materials through a new deracemization strategy that employs an enantioconvergent amino‐catalyzed symmetry‐making–symmetry‐breaking cascade. The reaction design features the tandem domination of product development and catalyst control in two reaction steps (see scheme).
A protecting group free and scalable approach towards total synthesis of (−)-venlafaxine
作者:Subhash P. Chavan、Kailash P. Pawar、Sumanta Garai
DOI:10.1039/c4ra00840e
日期:——
A protectinggroupfree asymmetric totalsynthesis of (−)-venlafaxine is reported. The strategy employs Sharpless epoxidation and regio-selective epoxide ring opening by an in situ generated Gilman reagent as key steps. This paper reports a 53% overall yield in 6 steps for totalsynthesis of (−)-venlafaxine.