A base, which has been called haplodimerine, has been isolated from the fruit of the plant Haplophyllum foliosum Vved. It has been established by x-ray structural analysis that haplodimerine includes fragments of the known alkaloids skimmianine and flindersine attached to one another through the double bonds of furan and dimethylpyran rings with the formation of a four-membered ring. © 1989, Plenum Publishing Corporation. All rights reserved.