11 beta,12 beta-diacetoxyharrisonin, a tetranortriterpenoid from Harrisonia abyssinica

A new tetranortriterpenoid, 11 beta,12 beta-diacetoxyharrisonin, together w ith the known atalantolide, obacunone, harrisonin, 12 beta-acetoxyharrisoni n, pedonin, cneorin R and perforaquassin A have been isolated from the root bark of Harrisonia abyssinica. The structure of the new compound which is based on a rearranged tetranortriterpenoid with a five membered ring-B and a seco ring-A and D was assigned on the basis of extensive NMR studies and X-ray diffraction analysis. In addition, the structure and relative configu ration of the known perforaquassin A was confirmed by X-ray diffraction ana lysis. (C) 1999 Elsevier Science Ltd. All rights reserved.