A new alkaloid of hydro-oxadiazine with a four-ring fused structure ha
s been isolated from Fissistigma oldhamii (Memsl.) Merr. (Annonaceae)
and named fissoldhimine (1), the structure of which was solved by X-ra
y analysis. NMR spectra were assigned based on the established structu
re, and its possible biogenesis is also discussed.