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

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 ringAhas an envelope conformation, while the six-membered ringsB–Eadopt chair conformations. RingsAandBarecis-fused. The hydroximino group has anEconfiguration. Strong intermolecular O—H...O hydrogen bonds link the molecules into helical chains.