Enantioselective fluoride ring opening of aziridines enabled by cooperative Lewis acid catalysis
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.
Hg cathode-free electrochemical detosylation of N,N-disubstituted p-toluenesulfonamides: mild, efficient, and selective removal of N-tosyl group
摘要:
Hg cathode-free electrochemical detosylation of N,N-disubstituted p-toluenesulfonamides was successfully carried out by a constant Current electrolysis using an undivided cell equipped with a platinum cathode and a magnesium anode in the presence of an arene mediator. The deprotection proceeded efficiently and selectively under neutral and mild conditions with a stoichiometric amount of electricity without the use of an Hg cathode to obtain the corresponding secondary amines in good to excellent yields. (C) 2009 Elsevier Ltd. All rights reserved.
Synthesis of β-Fluoroamines by Lewis Base Catalyzed Hydrofluorination of Aziridines
作者:Julia A. Kalow、Dana E. Schmitt、Abigail G. Doyle
DOI:10.1021/jo300433a
日期:2012.4.20
Lewis base catalysis promotes the in situ generation of amine-HF reagents from benzoyl fluoride and a non-nucleophilic alcohol. The hydrofluorination of aziridines to provide beta-fluoroamines using this latent HF source is described. This protocol displays a broad scope with respect to aziridine substitution and N-protecting groups. Examples of regio- and diastereoselective ring opening to access medicinally relevant beta-fluoroamine building blocks are presented.
One pot synthesis of homochiral aziridines and aminoalcohols from homochiral 1,2-cyclic sulfates
作者:B.Bhushan Lohray、Yun Gao、K.Barry Sharpless
DOI:10.1016/s0040-4039(00)99081-6
日期:1989.1
Enantioselective fluoride ring opening of aziridines enabled by cooperative Lewis acid catalysis
作者:Julia A. Kalow、Abigail G. Doyle
DOI:10.1016/j.tet.2013.01.062
日期:2013.7
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.
Hg cathode-free electrochemical detosylation of N,N-disubstituted p-toluenesulfonamides: mild, efficient, and selective removal of N-tosyl group
Hg cathode-free electrochemical detosylation of N,N-disubstituted p-toluenesulfonamides was successfully carried out by a constant Current electrolysis using an undivided cell equipped with a platinum cathode and a magnesium anode in the presence of an arene mediator. The deprotection proceeded efficiently and selectively under neutral and mild conditions with a stoichiometric amount of electricity without the use of an Hg cathode to obtain the corresponding secondary amines in good to excellent yields. (C) 2009 Elsevier Ltd. All rights reserved.