Pachystermine-A (I) and -B (II), isolated from Pachysandra terminalis sieb.et Zucc. (Buxaceae), are novel type alkaloids having a β-lactam ring system in the molecule. These were synthesized from epipachysandrine-A (III) which was obtained as a minor component from the same source. © 1971, The Pharmaceutical Society of Japan. All rights reserved.