<jats:p> Degradations of ormosanine, C<jats:sub>20</jats:sub>H<jats:sub>35</jats:sub>N<jats:sub>3</jats:sub>, are described which are in agreement with structure II (8) for this alkaloid. Nuclear magnetic resonance study of N-acetyl and N-nitroso derivatives has been used to clarify the environment of the secondary nitrogen atoms. Chemical and spectroscopic evidence leads to the formulation XVb for the related alkaloid ormojanine, C<jats:sub>20</jats:sub>H<jats:sub>31</jats:sub>N<jats:sub>3</jats:sub>.Both alkaloids were found to give 3-n-pentyl-6,8-dipropylquinoline together with the corresponding 3-n-butyl derivative in a catalytic dehydrogenation. The possible mechanism of formation of these dehydrogenation products is discussed and their synthesis is described.