Chemistry of secologanin.: Part 7:: Chemical fragmentation of secologanin:: biomimetic transition from the aliphatic into the aromatic skeleton

Transformation of secologanin and its ethylene acetal was investigated under acidic and basic conditions. Under acidic conditions both compounds gave benzaldehyde and an undefined fragment. A primary amine was incorporated into the substrate by lactamization with or without deglucosylation. Secondary and tertiary amines catalyzed lactonization of secologanin, but piperidine cleaved the acetal into methyl 3-piperidino-acrylate and an undefined C-7 unit which proved to be a phenyl group analogous to the indole alkaloid derivatives of secologanin. The biogenetic and biomimetic significance of the fragmentation is discussed. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.