Triterpenoids from the leaves of far eastern species of the shrubby birchesBetula ovalifolia andB. middendorfii

From the unsaponifiable fraction of an ethereal extract of the leaves ofBetula ovalifolia have been isolated the new triterpene 20(S),24(R)-epoxydammarane-3,17,25-triol (V) and the corresponding monoketone at C³ (VI). The leaves ofB. middendorfii have yielded the triterpene (IX) and (X), identified as, respectively, dammar-23-ene-3,12,20(S),25-tetraol and damman-25-ene-3,12,20-(S),24-tetraol, which have been obtained previously from the leaves ofBetula platyphylla Sukatchev var.japonica.The species of birch were determined by V. I. Baranov of the Laboratory of Chemotaxonomy.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 323–329, May–June, 1981.