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. 2009 Aug 8;65(Pt 9):o2088-9.
doi: 10.1107/S1600536809030311.

19β,28-Ep-oxy-18α-olean-3β-ol

R C Santos, R M A Pinto, A Matos Beja, J A R Salvador, J A Paixão

19β,28-Ep-oxy-18α-olean-3β-ol

R C Santos et al. Acta Crystallogr Sect E Struct Rep Online. .

Abstract

The title triterpene, C(30)H(50)O(2), is an 18α-oleanane derivative prepared by the Wagner-Meerwein rearrangement of betulin with Bi(OTf)(3).xH(2)O (OTF is trifluoromethanesulfonate). There are two symmetry-independent mol-ecules in the asymmetric unit that show no significant differences concerning bond lengths and angles. The conformation of the six-membered rings is close to a chair form, while the five-membered epoxide rings adopt envelope conformations. All rings are trans-fused. In the crystal, mol-ecules are held together by O-H⋯O hydrogen bonds. A quantum-mechanical ab initio Roothan Hartree-Fock calculation on the isolated mol-ecule gives values for bond lengths and valency angles close to the experimental values. The calculations also reproduce well the mol-ecular conformation with calculated puckering parameters that match well the observed values.

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Figures

Fig. 1.
Fig. 1.
ORTEPII plot of one of the two molecules in the asymmetric unit. Displacement ellipsoids are drawn at the 50% level.
See this image and copyright information in PMC

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