Spegazzinidine (C21H25N2O4), a new alkaloid from Aspidosperma chakensis Spegazzini, has been shown to possess structure III, thus making it the first naturally occurring dihydroindole alkaloid with a catechol system. Nuclear magnetic resonance spectrometry was largely responsible for elucidating the precise nature of the N-acetyldihydroindole fragment, while mass spectrometry demonstrated the existence of an aspidospermine-like skeleton. The nature of the remaining oxygen function was recognized as a hydroxyl group by oxidation to a ketone, which exhibited an unusual mass spectrometric fragmentation pattern. Chemical proof for structure III was provided by successive methylation of the catechol grouping, tosylation of the alcohol function and finally lithium aluminum hydride reduction (of VIII) leading to 16-methoxy-N-deacetyl-N-ethylaspidospermine (IX), which proved to be the antipode of the lithium aluminum hydride reduction product of (+)-pyrifolidine (antipode of V). In view of the known antipodal relationship of (+)-pyrifolidine (antipode of V) and (-)-aspidospermine (I), spegazzinidine can be defined as 3, 16-dihydroxy-17-demethyl-(-)-aspidospermine, while mass spectrometric evidence coupled with n.m.r. measurements allow the assignment of lated alkaloid spegazzinine. © 1962, American Chemical Society. All rights reserved.