Premium
Optical enrichment in chiral crystal environment of [( R,S )‐1‐cyanoethyl][methyl ( S )‐alaninate]cobaloxime complex only by photoirradiation
Author(s) -
Hashizume Daisuke,
Ohashi Yuji
Publication year - 2000
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/1099-1395(200007)13:7<415::aid-poc286>3.0.co;2-z
Subject(s) - chemistry , diastereomer , crystal structure , crystallization , crystal (programming language) , stereochemistry , molecule , crystallography , organic chemistry , computer science , programming language
Abstract The diastereomeric pair of the [( R,S )‐1‐cyanoethyl][methyl ( S )‐alaninate]cobaloxime complex cannot be separated by the fractional crystallization method. Crystal structure analysis revealed that there are two crystallographically independent molecules which are diastereomers to each other in a unit cell. When the crystal was irradiated with a xenon lamp, the cell dimensions gradually changed. After about 70 h of exposure, the change became insignificantly small. Crystal structure analysis after irradiation indicated that only the ( R )‐1‐cyanoethyl complex was epimerized and the ( S )‐1‐cyanoethyl complex remained unaltered. This led to an increased amount of the ( S )‐1‐cyanoethyl complex in the crystal. The optical enrichment occurred only by photoirradiation. The diastereomeric excess of the ( S )‐1‐cyanoethyl complex became 32% in the final stage. The reason why only the ( R )‐1‐cyanoethyl complex was epimerized was clearly explained by the size and shape of the reaction cavity for the 1‐cyanoethyl group. Copyright © 2000 John Wiley & Sons, Ltd.