C3-symmetric tripodal tetra-amines—preparation from chiral amino alcohols via aziridines
摘要:
Enantiopure N-sulfonylaziridines, conveniently obtained from readily available enantiopure amino alcohols, undergo smooth ring opening reactions using ammonia as a nucleophile to yield tripodal tetradentate C-3-symmetric amines. N-alkylation and subsequent removal of the sulfonyl groups provide access to alkyl-substituted analogs. (C) 1997 Elsevier Science Ltd.
Catalytic Asymmetric Acyl Halide−Aldehyde Cyclocondensation Reactions of Substituted Ketenes
作者:Scott G. Nelson、Cheng Zhu、Xiaoqiang Shen
DOI:10.1021/ja0391208
日期:2004.1.1
Catalyticasymmetricacylhalide-aldehydecyclocondensation (AAC) reactions of alkyl-substituted ketenes with structurally diverse aldehydes provide cis-disubstituted beta-lactones with high enantioselectivity. The AAC reactions utilize a novel Al(III)-triamine catalyst in which the metal's dynamic coordination geometry leads to a highly selective catalyst complex. These AAC reactions represent a functional
Enantio- and Diastereoselective Catalytic Alkylation Reactions with Aziridines
作者:Thomas A. Moss、David R. Fenwick、Darren J. Dixon
DOI:10.1021/ja8036965
日期:2008.8.1
The first asymmetric phase transfer catalyzed alkylation reaction of a range of carbon acids with N-sulfonyl aziridines is reported. When 10 mol % of a cinchona derived quaternary ammonium salt was employed as the catalyst under mildly basic conditions, N-o-(trifluoromethane)benzenesulfonyl aziridine was efficiently ring-opened to afford the amino ethylene products in consistently high yields and high
Enantioselective Cu-Catalyzed Conjugate Addition of Diethylzinc to Acyclic Aliphatic Enones
作者:Andrew P. Duncan、James L. Leighton
DOI:10.1021/ol048191o
日期:2004.10.1
[reaction: see text] A new P-chiral phosphine bis(sulfonamide) ligand has been developed that allows the Cu-catalyzed enantioselectiveconjugateaddition of Et(2)Zn to acyclic aliphatic enones. The reactions proceed with excellent levels of enantioselectivity (90-95% ee) with a range of enone substrates, involve the use of only 1.2 equiv of Et(2)Zn, and give best results at ambient temperature.
Highly Practical and Enantioselective Cu-Catalyzed Conjugate Addition of Alkylzinc Reagents to Cyclic Enones at Ambient Temperature
作者:Isaac J. Krauss、James L. Leighton
DOI:10.1021/ol034983r
日期:2003.9.1
[GRAPHICS]A new ligand for Cu-catalyzed enantioselective additions of dialkylzincs to cyclic enones has been developed. In addition to providing good to excellent enantioselectivities with a range of cyclic enones and dialkylzincs, the ligand has several notworthy features: it can be readily prepared in just two steps, is an air-stable crystalline solid, and provides optimal performance at ambient temperature.
Sulfonamide Ligands from Chiral Aziridines − Application to the Titanium-Mediated Addition of Diethylzinc to Benzaldehyde
A modular approach was developed for the preparation of chiral, enantiopure sulfonamide ligands with C-1, C-2, and C-3 symmetry by ring opening of chiral N-sulfonylaziridines with ammonia, primary amines, and diamines. The new ligands were assessed in the titanium-mediated addition of diethylzinc to benzaldehyde, giving the product with selectivities up to 76% ee. ((C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).