Five new C20-diterpenoid alkaloids, 12-acetyldehydrolucidusculine, 12-acetyllucidusculine, 15-benzoylpseudokobusine, 15-veratroylpseudokobusine, and yesoxine and 14 known alkaloids were isolated from A. yesoense var. macroyesoense (Nakai) Tamura. Structures of those compounds were determined on the basis of their spectral and chemical data. Structure of an unusual epoxide, yesoxine, was determined by X-ray analysis and was a first example having an epoxy group at C(16 and 17). © 1987.