Triterpenoids from the leaves ofBetula 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-3,11,25-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.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center of the Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 513–516, July–August, 1980.     

Flavonoid Glycosides from the Aerial Part of Lespedeza tomentosa

Chemistry of Natural Compounds - The aerial part of Lespedeza tomentosa (Thunb.) Maxim. growing in southern Primorsky Krai, Russian Federation, yielded 10 identified flavonoid glycosides, eight of...     

Synthesis of 2,2’-(ethane-l,l-diyl)bis(3,5,6,7,8-pentahydroxy-l,4-naphthoquinone), a metabolite of the sea urchins Spatangus purpureus,Strongylocentrotus intermedius,and S. droebachiensis

A key step in the synthesis of 2,2’-(alkane-l,l-diyl)bis(3,5,6,7,8-pentahydroxy-l,4-naphthoquinones) is an acid-catalyzed condensation of 2-hydroxynaphthazarins, the products of the retro aldol reaction of 2-hydroxy-3-(l-hydroxyalkyl)naphthazarins, with the corresponding aldehydes. This method is applicable, in particular, for the preparation of compound with the ethane-1,1-diyl bridge — a metabolite produced by the sea urchins Spatangus purpureus, Strongylocentrotus intermedius, and S. droebachiensis.     

Chemistry of naphthazarin derivatives. 11. Trisubstituted hydroquinone derivatives in the preparative synthesis of naphthazarins

The Friedel—Crafts acylation of trimethylhydroquinone, 3,5-diethyl-2-hydroxyhydroquinone, and 3,5-diethyl-1,2,4-trimethoxybenzene with dichloromaleic or citraconic anhydride in an AlCl₃—NaCl melt is accompanied by o-C-dealkylation to afford functionally substituted naphthazarins.     

Partial synthesis of octanor-13β-dammarane

The partial synthesis of octanor-13β-dammarane — one of the basic compounds for calculating the effects of substituents in the¹³C NMR spectra of tetracyclic triterpenoids of the dammarane series — has been effected.     

Triterpenoids from the leaves ofBetula 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.