Molecular structures of four triterpenoids. X-ray crystallographic analysis of methyl 2?,3?,23?-triacetoxy-19?-hydroxyurs-12-en-28?-oate
摘要:
A triterpenoid glycoside has been isolated from the roots of a herb used in traditional Chinese medicine. The molecular structure of this compound and its derivatives have been determined by spectroscopic studies and an X-ray analysis of the 2alpha,3beta,23alpha-triacetoxy-28beta-methyl ester of the aglycone. This aglycone belongs to the ursene structure series. The hydroxy group on ring E of these triterpenoids is alpha orientated and the side chains at C(2), C(3), C(4) and C(17) are alpha, beta, alpha and beta orientated, respectively. The C ring, which has a double bond at C(12)=C(13), adopts a sofa conformation.