Received 31 July 2009
Four of the five six-membered rings of the title pentacyclic triterpene, C33H52O4, adopt chair conformations; the fifth, which has a C=C double bond, adopts an approximate envelope conformation.
For the synthesis, see: Ma et al. (2005). The crystal structure of ursolic acid is known from its ethanol solvate; see: Simon et al. (1992). For methyl uroslate-3-bromoacetate, see: Stout & Stevens (1963). For methyl ursolate-3-p-bromobenzoate, see: Paton & Paul (1979).
Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: publCIF (Westrip, 2009).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: XU2574 ).
We thank the University of Malaya for supporting this study.
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