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Stereoselective Hydrolysis of Amino Acid Esters Catalyzed by β‐Cyclodextrin‐L(or D)‐histidine Compounds
Author(s) -
Ohkubo Katsutoshi,
Nagamura Hiroo
Publication year - 1985
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198500038
Subject(s) - chemistry , moiety , stereoselectivity , catalysis , substrate (aquarium) , cyclodextrin , nucleophile , hydrolysis , histidine , stereochemistry , enantiomer , amino acid , enzyme , organic chemistry , biochemistry , geology , oceanography
The catalytic activity of β ‐cyclodextrin‐L(or D)‐histidine compounds, β ‐CD‐D‐His(e) ( 2a ), β ‐CD‐L‐His(e) ( 2b ), and β ‐CD‐D‐D‐His(a) ( 2c ), for the stereoselective hydrolysis of N‐acyl‐amino acid esters ( 3a‐f ) was examined at 25° C (pH 7.90). The ability of 2a‐c to bind the ester substrate into the cyclodextrin cavity and to attack the bound substrate by the nucleophilic imidazolyl group of the histidine moiety resulted in extremely high activity for those catalysts. However, the stereoselection of the enantiomeric esters during the inclusion of the substrate by 2a‐c was found to be opposite, in terms of chiral specificity, to that during the esterolysis of 2a‐c in the molecular cavity: that is, the stereoselective activity of 2a‐c is very small. The catalytic activities of 2a‐c are also influenced by the structural differences in 3a‐f , which result in the different modes of substrate inclusion by the catalyst through hydrophobic forces.