Synthesis of 25-oxygenated D:A-friedooleananes: Part IV - Studies on the structure of roxburghonic acid
Structure of the natural product roxburghonic acid (1) has been established by its synthesis from purtanjivadione (2).Compound 2 is converted into 3β-acetoxy-7β,25-oxido-D:A-friedooleanane (3) by the literature method.The latter on oxidation with CrO3-AcOH gives 3β-acetoxy-D:A-friedoolean-7β 25-olide (4) which is hydrolysed with 5percent methanolic KOH solution to yield 3β-hydroxyolide (5).The lactone 5 on treatment with lithium in boiling ethylenediamine affords 3β-hydroxy-D:A-friedoolean-25-oic acid (6) which on oxidation with CrO3 in pyridine yields 1.The structure of 1 has been confirmed by its elemental analyses and spectral (IR, PMR and mass) data and also by esterification with diazomethane to give methyl roxburghonate (7).
Ghosh, S. K.,Datta, S. K.,Das, Saktipada
p. 370 - 371
(2007/10/02)
D:A-Friedooleananes from Elaeodendron glaucum
Two new trioxygenated D:A-freidooleananes from the stem bark of Elaeodendron glaucum have been shown to be the angular methyl dioxygenated 25,28-dihydroxy-D:A-friedooleanan-3-one (2) and 25-hydroxy-3-oxo-D:A-friedooleanan-28-al (3).
Weeratunga, Gamini,Kumar, Vijaya,Sultanbawa, M. Uvais S.
p. 1067 - 1072
(2007/10/02)
TWO NEW ANGULAR METHYL DIOXYGENATED D:A-FRIEDO-OLEANANES
Two new trioxygenated D:A-friedo-oleananes from Elaeodendron glaucum have been shown to be the angular methyl dioxygenated 25,28-dihydroxy-D:A-friedo-oleanan-3-one(1) and 3,28-dioxo-D:A-friedo-oleanan-25-ol(2) by interconversion and deoxygenation of the alcohol(2) using Lithium-ethylene diamine reduction coupled with spectroscopic methods.
Weeratunga, Gamini,Kumar, Vijaya,Sultanbawa, M. Uvais S.
p. 2031 - 2032
(2007/10/02)
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