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 via kinetic resolution
作者:Yongtae Kim、Eui Ta Choi、Min Hee Lee、Yong Sun Park
DOI:10.1016/j.tetlet.2007.02.111
日期:2007.4
Catalytic asymmetricdehydration of β-hydroxyesters via kineticresolution has been investigated. The kineticresolution of rac-β-hydroxy esters in the presence of prolinol chiral ligand 2a and BrZnCH2CO2t-Bu can provide highly enantioenriched β-hydroxyesters 3 and 5–11 with selectivity factors ranging from 15 to 42.
已经研究了通过动力学拆分对β-羟基酯进行催化不对称脱水的方法。的动力学拆分外消旋-β-羟基酯在存在脯氨醇手性配体2A和BrZnCH 2 CO 2吨-Bu能够提供对映体富集的高度β羟基酯3和5 - 11有选择性因素,从15至42。
Enantioselective reformatsky reaction induced by chiral β-amino alcohols
Reformatskyreagent derived from tert-butyl α-bromoacetate adds to carbonyl compounds in the presence of chiral amino alcohols leading to β-hydroxy tert-butyl esters with good e.e. The enantioface differentiation depends on the reaction conditions and on the structure of the chiral auxiliary. The best chemical yields and e.e. are obtained for aromatic aldehydes by using the C-2 symmetrical chiral bis-amino