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
The development of new approaches to obtain optically pure β-hydroxy esters is an important area in synthetic organic chemistry since they are precursors of other high value compounds. Herein, the kineticresolution of racemic β-hydroxy esters using a planar-chiralDMAPderivative catalyst is presented. Following this procedure, a range of aromatic β-hydroxy esters was obtained in excellent selectivities
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。
(R)-(+)-N-Methylbenzoguanidine ((R)-NMBG) catalyzed acylative kinetic resolution of racemic 3-hydroxy-3-aryl-propanoates
作者:Akira Yamada、Kenya Nakata
DOI:10.1016/j.tetlet.2016.09.014
日期:2016.10
cyclohexane carboxylic anhydride under mild reaction conditions. A tert-butyl ester moiety is necessary to achieve a high selectivity. The effects of the substituents on the aromatic rings of the substrates were systematically investigated, and diverse substrates participated in the reaction with good s-values (>20) irrespective of the type of substituents and their patterns, except for o-methoxy group
[2.2]Paracyclophane-based carbene–copper catalyst tuned by transannular electronic effects for asymmetric boration
作者:Jianqiang Chen、Wenzeng Duan、Zhen Chen、Manyuan Ma、Chun Song、Yudao Ma
DOI:10.1039/c6ra14404g
日期:——
of planar chiral carbene–copper complexes based on the [2.2]paracyclophane backbone with a pseudo-ortho substitution pattern have been synthesized and applied to asymmetric β-boration of α,β-unsaturatedesters. As a result, transannular electronic effects of the substituent of the chiralcatalyst have significant influence on the catalytic performance. A variety of chiral β-hydroxyl esters were obtained