Abstract
The structure of hasubanonine was reexamined and the complate constitution (IIc) including the absolute stereostructure was presented. The structure of homostephanoline was also investigated and three possible structure for this alkaloid were shown in formulae (XIIIa), (XIIIb), (XIIIc). These two alkaloids have a novel skeleton (XII) which has not been known hitherto in the natural sources, for which the name "hasubanan" was proposed.