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 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。
Asymmetric Preparation of D-Phg-L-Pro Dipeptide-derived Chiral Ligands for Enantioselective Addition of Diethylzinc to Aldehydes
作者:Seock-Yong Kang、Yi-Kyung Ko、Kon-Ji Park、Yong-Sun Park
DOI:10.5012/bkcs.2012.33.7.2397
日期:2012.7.20
-Pro dipeptide analogues 2 and 3 as shown in Scheme1. The treatment of two diastereomeric mixture (1:1) of N-(α-bromo-α-phenylacetyl)-(L)-proline methyl ester 1 withan amine nucleophile (diphenylmethylamine or dibenzyl-amine) in the presence of tetrabutylammonium iodide (TBAI)and diisopropylethylamine (DIEA) in CH