Asymmetric Conjugate Addition of Silyl Enol Ethers Catalyzed by Tethered Bis(8-quinolinolato) Aluminum Complexes
作者:Norito Takenaka、Joshua P. Abell、Hisashi Yamamoto
DOI:10.1021/ja0668320
日期:2007.1.1
aluminum(III) complexes effectively catalyze the highly enantioselective Mukaiyama−Michael reaction of silyl enol ethers, including tetrasubstituted enolates that give rise to enantioenriched α-carbonyl all-carbon-substituted quaternary stereocenters. The present catalyst also promotes the conjugate addition of N-benzylindole to α,β-unsaturated acylphosphonates with high enantioselectivity (indole Friedel−Crafts
The preparation of novel chiral auxiliaries SAMIQ/RAMIQ and their application in the asymmetric Michael addition
作者:Xuan Pan、Zhanzhu Liu
DOI:10.1016/j.tet.2014.05.049
日期:2014.8
A pair of novel chiral auxiliaries SAMIQ/RAMIQ was synthesized from L- or D-phenylalanine methyl ester hydrochloride over six steps in 45.8% and 44.4% yield, respectively. The SAMIQ-/RAMIQ-hydrazone methodology was applied for the asymmetric Michael addition of ketones to alpha,beta-unsaturated carboxylic acid methyl esters, which afforded 3-substituted-5-oxo-alkanoates in moderate to good yield (65-82%) with excellent enantioselectivity (ee=95.3%similar to>99.5%). (C) 2014 Elsevier Ltd. All rights reserved.
Ni(II) Tol-BINAP-Catalyzed Enantioselective Michael Reactions of β-Ketoesters and Unsaturated <i>N</i>-Acylthiazolidinethiones
作者:David A. Evans、Regan J. Thomson、Francisco Franco
DOI:10.1021/ja053820q
日期:2005.8.1
The enantioselective addition of beta-ketoesters to unsaturated N-acylthiazolidinethiones catalyzed by Ni(II) Tol-BINAP Lewis acid complexes is reported. Notable features of this reaction are its operation simplicity, the obviated need for the addition of an external base, and the ease with which the adducts are converted into a range of potentially useful derivatives. In particular, the dihydropyrone adducts are versatile scaffolds for further stereoselective elaboration.
Highly Enantioselective Catalytic Thiolysis of Prochiral Cyclic Dicarboxylic Anhydrides Utilizing a Bifunctional Chiral Sulfonamide