Enantiopure 2-azabicyclo[3.3.0]octanes 1a-d and ent-le were oxidized with m
CPBA to provide either diastereomeric pairs of N-oxides (2a/3a and 2b/3b) o
r diastereomerically pure compounds (2c,d and ent-2e). The structure of com
pounds 2a and enf-2e was confirmed by an X-ray study. The factors that affe
ct the oxidation process are discussed.