Acta Cryst. (2009). E65, o1262  [ doi:10.1107/S1600536809016675 ]

(E)-17,19-Epoxymethano-17,23,24-tridemethyl-4-nor-5,18-olean-3-one oxime

A. Froelich, O. B. Kazakova, G. Tolstikov and A. K. Gzella

Abstract: In the pentacyclic triterpenoide skeleton of the title molecule, C₂₇H₄₃NO₂ [systematic name: (3E,3aS,5aR,5bR,7aR,11R,11aR,11bR,13aR,13bR)-5a,5b,10,10,13b-pentamethylicosahydro-1H-11,7a-(epoxymethano)cyclopenta[a]chrysen-3-one oxime], the five-membered ring A has an envelope conformation, while the six-membered rings B-E adopt chair conformations. Rings A and B are cis-fused. The hydroximino group has an E configuration. Strong intermolecular O-HO hydrogen bonds link the molecules into helical chains.

Online 14 May 2009

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