- Dammarane Triterpenes of Trevoa trinervis: Structure and Absolute Stereochemistry of Trevoagenins A, B, and C
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Trevoagenins A, B, and C, extracted from Trevoa trinervis Miers, are shown, by chemical and spectral means, to be isomeric dammarane triterpenes posessing the general 3β,25,30-trihydroxy-(20,24)-epoxydammaran-16-one structure with stereoisomeric side-chains of the ocotillol type.Trevoagenin A (20R,24R)-(1),, whose stereochemistry has been esteblished by chemical methods and confirmed by X-ray analysis, was transformed into (20R,24ξ)-ocotillone (26) and the C-24 stereochemistry was assigned as R.As a consequence, the C-24 stereochemistry for ocotillol-related compounds of the (20R)-series, unestablished so far, has been determined.The stereochemistry of trevoagenin B, (20S,24R)-(13), was established by chemical correlation with trevoagenin A.Moreover, trevoagenin B was transformed into ocotillol (20S,24R)-(21) and its recently questioned C-24 stereochemistry has been reaffirmed.Trevoagenin C, (20S,24S)-(17), is the C-24 isomer of trevoagenin B as shown by degradation of both compounds to the lactone (16).
- Betancor, Carmen,Freire, Raimundo,Hernandez, Rosendo,Suarez, Ernesto,Cortes, Manuel,et al.
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p. 1119 - 1126
(2007/10/02)
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- TRITERPENOIDS FROM THE LEAVES OF Betula lanata
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From the unsaponifiable fraction of an ethereal extract of the leaves of Betula 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.
- Pokhilo, N. D.,Malinovskaya, G. V.,Makhan'kov, V. V.,Anufriev, V. F.,Uvarova, N. I.
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p. 368 - 372
(2007/10/02)
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