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Title: 19β,28-Ep-oxy-18α-olean-3β-ol
Authors: Santos, R. C. 
Pinto, R. M. A. 
Beja, A. Matos 
Salvador, J. A. R. 
Paixão, J. A. 
Keywords: single-crystal X-ray study; T = 293 K; mean (C–C) = 0.004 A°; R factor = 0.048; wR factor = 0.140; data-to-parameter ratio = 11.0
Issue Date: 8-Aug-2009
Publisher: International Union of Crystallography
Project: SFRH/ BD/18013/2004 
Serial title, monograph or event: Acta Crystallographica Section E: Structure Reports Online
Volume: 65
Issue: Pt 9
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.
ISSN: 1600-5368
DOI: 10.1107/S1600536809030311
Rights: openAccess
Appears in Collections:FCTUC Física - Artigos em Revistas Internacionais
FFUC- Artigos em Revistas Internacionais

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