Triterpenoids from the leaves of Betula lanata

From the unsaponifiable fraction of an ethereal extract of the leaves ofBetula lanata, in addition to 3-epiocotillol (I) we have isolated a new triterpene, 20(S), 24(R)-epoxydammarane-3α,11α,25-triol (V) and also derivatives of it — the monoacetates at C-3 (II) and C-11 (III), and the monoketone at C-3 (IV). The structures of compounds (I-V) have been established on the basis of the results of physicochemical investigations.