Description:
<jats:p>In the pentacyclic triterpenoide skeleton of the title molecule, C<jats:sub>27</jats:sub>H<jats:sub>43</jats:sub>NO<jats:sub>2</jats:sub>[systematic name: (3<jats:italic>E</jats:italic>,3a<jats:italic>S</jats:italic>,5a<jats:italic>R</jats:italic>,5b<jats:italic>R</jats:italic>,7a<jats:italic>R</jats:italic>,11<jats:italic>R</jats:italic>,11a<jats:italic>R</jats:italic>,11b<jats:italic>R</jats:italic>,13a<jats:italic>R</jats:italic>,13b<jats:italic>R</jats:italic>)-5a,5b,10,10,13b-pentamethylicosahydro-1<jats:italic>H</jats:italic>-11,7a-(epoxymethano)cyclopenta[<jats:italic>a</jats:italic>]chrysen-3-one oxime], the five-membered ring<jats:italic>A</jats:italic>has an envelope conformation, while the six-membered rings<jats:italic>B</jats:italic>–<jats:italic>E</jats:italic>adopt chair conformations. Rings<jats:italic>A</jats:italic>and<jats:italic>B</jats:italic>are<jats:italic>cis</jats:italic>-fused. The hydroximino group has an<jats:italic>E</jats:italic>configuration. Strong intermolecular O—H...O hydrogen bonds link the molecules into helical chains.</jats:p>