title: (E)-17β,19-Epoxy-methano-17,23,24-tridemethyl-4-nor-5β,18α-olean-3-one oxime.
abstract: In the penta-cyclic triterpenoide skeleton of the title mol-ecule, C(27)H(43)NO(2) [systematic name: (3E,3aS,5aR,5bR,7aR,11R,11aR,11bR,13aR,13bR)-5a,5b,10,10,13b-penta-methyl-icosa-hydro-1H-11,7a-(epoxy-methano)cyclo-penta-[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 inter-molecular O-H⋯O hydrogen bonds link the mol-ecules into helical chains.
authors.forename: Anna
authors.initials: A
authors.lastname: Froelich
authors.forename: Oxana B
authors.initials: OB
authors.lastname: Kazakova
authors.forename: Genrikh
authors.initials: G
authors.lastname: Tolstikov
authors.forename: Andrzej K
authors.initials: AK
authors.lastname: Gzella