Various chiral substituted 1,4-benzodiazepin-2-ones with 3-
-acyloxy (general formula I), 3-hydroxy- and 3-alkoxy (general
formula II), 3-alkyl (general formula III) and 3-quaternary ammonium
(general formula IV) groups as substituents were subjected
to C(3)-H-D exchange rate measurements in order to obtain information
on the optical stability of the chiral centre and on the
mechandsm of racemization. Only type IV compounds (IVa-j)
exhibited H/D exchange, but acid catalyzed racemization took
place in type I and II compounds, indkating some other mechani.
sms in this process. Type III compounds as free bases (IIIa-c),
N4-protonated acids, or N4-oxides (III, e; f) underwent no H/D
exchange and are optically sfable as well. In cases whe,re deprotonation-
reprotonation mechanism of racemization can be excluded
two other mechanisms are discussed, i. e. acid-\u27catalyzed ring-chain
tautomerism and identity substitution with alkoxide ion
