Indole alkaloids from Ervatamia orientalis. II. The constitution of the ervatamine group

Abstract

This paper describes the combination of physical and chemical degradative methods that has led to the elucidation of the constitution of the novel 2-acylindole alkaloids, ervatamine (5), 20-epi-ervatamine (6) and 19-dehydroervatamine (7). The alkaloids show differences in the N.M.R. spectra and in the rates of methylation which indicate that ervatamine has a different conformation from the other two alkaloids; the conformations which are suggested for the alkaloids (35)-(37) have alternative chair conformations of the piperidine rings. Correlations in the mass spectra of the natural alkaloids and of several simple derivatives are discussed.