Premium
Base‐catalyzed racemization of 3‐ O ‐acyloxazepam
Author(s) -
Yang Shen K.,
Bao Ziping
Publication year - 1994
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.530060416
Subject(s) - racemization , chemistry , enantiomer , enol , catalysis , solvent , hydrolysis , solvolysis , tautomer , medicinal chemistry , base (topology) , organic chemistry , mathematical analysis , mathematics
Enantiomers of 3‐ O ‐acyloxazepam (oxazepam 3‐acetate; OXA) underwent base‐catalyzed hydrolysis and racemization. Kinetics of reaction products formed from an OXA enantiomer in buffered and unbuffered alkaline solutions were analyzed by chiral stationary phase high‐performance liquid chromatography. Racemization occurred with varying rates in aqueous solutions with pH ranging from 7.5 to 14. Racemization mechanism was studied by the dependence of rates of hydrolysis and racemization on temperature and pH. Mass spectral analysis of racemization products derived from an OXA enantiomer in a deuterated solvent indicated that racemization was accompanied by a proton exchange with the solvent. The results indicated that a base‐catalyzed keto‐enol tautomerism between the C2‐carbonyl group and the C3 carbon was responsible for the observed racemization. © 1994 Wiley‐Liss, Inc. This article is a US Goverment work and, as such, is in the public domain in the United States of America.