Synthesis of enantiomerically enriched amines by chiral ligand mediated addition of organolithium reagents to imines
摘要:
The effect of the imine and ligand structure on the enantioselective addition or organolithiums to imines has been studied. Thus, (-)-sparteine-mediated additions or MeLi and or n-BuLi to p-anisidine derived phenylimine 1a afforded the corresponding amines with modest e.e.s. The use of bulkier or more reactive imines (naphthyl or toss I imines) resulted ill loss Of enantioselectivity. The best enantioinduction with this ligand,Nas obtained with enolizable imines 8 and 10. When bis(oxazolidines) were used as chiral ligands, a strong influence of their structure in the enantioselectivity or the addition of MeLi and n-BuLi to phenylimine 1a was observed. (C) 2001 Elsevier Science Ltd. All rights reserved.
A series of chiral cyclometalated iridiumcomplexes have been synthesised by cyclometalating chiral 2-aryl-oxazoline and imidazoline ligands with [Cp*IrCl2]2. These iridacycles were studied for asymmetric transfer hydrogenation reactions with formic acid as the hydrogen source and were found to display various activities and enantioselectivities, with the most effective ones affording up to 63% ee
作者:R. Ian Storer、Diane E. Carrera、Yike Ni、David W. C. MacMillan
DOI:10.1021/ja057222n
日期:2006.1.1
The first enantioselectiveorganocatalyticreductive amination reaction has been accomplished. The development of a new chiral phosphoric acid catalyst has provided a convenient strategy for the enantioselective construction of protected primary amines and provided a highly stereoselective method for the reductive amination of heterocyclic amines. A diverse spectrum of ketone and amine substrates can
The chiral phosphoric acid catalyzed enantioselective transferhydrogenation of various ketimines was achieved by the use of 2-aryl indoline as the hydrogen donor. Corresponding chiral amines were obtained in good chemical yields with excellent enantioselectivities.
Studies on the Bisoxazoline- and (−)-Sparteine-Mediated Enantioselective Addition of Organolithium Reagents to Imines
作者:Scott E. Denmark、Noriyuki Nakajima、Cory M. Stiff、Olivier J.-C. Nicaise、Michael Kranz
DOI:10.1002/adsc.200800017
日期:2008.5.5
The enantioselective addition of organolithiumreagents to N-anisyl aldimines promoted by chiral bisoxazolines and (-)-sparteine as external ligands is described. This reaction proceeds readily with a wide range of aldimine substrates (aliphatic, aromatic, olefinic) and organolithium nucleophiles (Me, n-Bu, Ph, vinyl) in excellent yields (81-99%) and with high enantioselectivities (up to 95.5:4.5 er)
work, a mild and transition‐metal‐free approach for the nucleophilic aromatic substitution (SNAr) of unactivated fluoroarenes with primary aliphatic amines to form aromatic amines is reported. This reaction is facilitated by the formation of cationic fluoroarene radical intermediates in the presence of an acridinium‐based organic photocatalyst under blue‐light irradiation. Various electron‐rich and