Discovery of Dipeptide-Derived Catalysts for the Enantioselective Addition of Dimethylzinc to Aldehydes
作者:Seock Yong Kang、Yong Sun Park
DOI:10.1002/ejoc.201200063
日期:2012.3
new class of modular chiral catalysts derived from various amino acid-L-Pro dipeptides was prepared, and the catalysts were tested for their ability to catalyze the enantioselective addition of dimethylzinc to aromatic aldehydes. Dipeptides derived from L-Asp-L-Pro were identified as effective catalysts for the addition at room temperature with up to 97:3 er and 95 % yield.
Asymmetric nucleophilic substitution of α-bromo amides via dynamic kinetic resolution for the preparation of dipeptide analogues
作者:Jiyoun Nam、Ji-yeon Chang、Eun-kyoung Shin、Hyun Jung Kim、Yangmee Kim、Soonmin Jang、Yong Sun Park
DOI:10.1016/j.tet.2004.05.094
日期:2004.7
Asymmetricnucleophilicsubstitution reactions of α-bromo α-aryl acetamides derived from l-amino acids are described. The simple and practical syntheses of dipeptide analogues have been developed with dibenzylamine, TBAI and a base to provide 2a–2n and 4 in 50–98% yields with diastereomeric ratios from 74:26 to >99:1. Mechanistic investigations suggest that α-bromo acetamides are configurationally
d-Phg-l-Pro Dipeptide-derived prolinol ligands for highly enantioselective Reformatsky reactions
作者:Eun-kyoung Shin、Hyun Jung Kim、Yongtai Kim、Yangmee Kim、Yong Sun Park
DOI:10.1016/j.tetlet.2006.01.070
日期:2006.3
prepared from the dynamic kineticresolution of N-(α-bromo-α-phenylacetyl) proline ester 1 in asymmetric nucleophilic substitution and subsequent reduction. The peptide-derived prolinols are tested as chiral ligands in the asymmetric addition of Reformatsky reagent to aromatic aldehydes. Chiral ligand 3c has been shown to be effective to produce enantioenriched β-hydroxyesters 5a–j with up to 98% ee
Asymmetric dehydration of β-hydroxy esters and application to the syntheses of flavane derivatives
作者:Eui Ta Choi、Min Hee Lee、Yongtae Kim、Yong Sun Park
DOI:10.1016/j.tet.2007.11.026
日期:2008.2
Catalytic asymmetricdehydration of β-aryl or alkyl substituted β-hydroxyesters via kineticresolution has been investigated. A brief survey of 10 different chiral ligands is conducted to examine the effects of chiral ligand structure on selectivity of the dehydration. The kineticresolution of a variety of rac-β-hydroxy tert-butyl esters in the presence of prolinol chiral ligand 2 and BrZnCH2CO2-t-Bu
已经研究了通过动力学拆分对β-芳基或烷基取代的β-羟基酯进行催化不对称脱水的方法。简要调查了10种不同的手性配体,以研究手性配体结构对脱水选择性的影响。在脯氨醇手性配体2和BrZnCH 2 CO 2 - t -Bu存在下,多种rac -β-羟基叔丁酯的动力学拆分可提供高度对映体富集的β-羟基酯14 – 21,选择性因子为11至66.此外,这种不对称合成方法在制备对映体富集的黄烷衍生物中的应用演示了25 – 29。
Dynamic kinetic resolution of α-bromo amides for asymmetric syntheses of di- and tripeptide analogues
作者:Jiyoun Nam、Ji-Yeon Chang、Kyung-Soo Hahm、Yong Sun Park
DOI:10.1016/j.tetlet.2003.08.091
日期:2003.10
Effective dynamic kinetic resolution in the nucleophilic substitution reactions of alpha-bromo amides derived from L-leucine and L-proline is described. The methodology is used with dibenzylamine as a nucleophile in the presence of TBAI and Et3N to provide di- and tripeptide analogues up to 95% yield and >99:1 dr. (C) 2003 Elsevier Ltd. All rights reserved.