3-Oxo-18α-olean-28,13β-olide

Abstract

The title terpene, C30H46O3, is a 28,13β-lactone of oleanolic acid prepared with bismuth trifluoromethanesulfonate (OTf), Bi(OTf)3·xH2O. All rings are trans-fused. The X-ray study shows the inversion of the orientation of 18-H in the lactonization reaction. A quantum chemical ab-initio Roothaan Hartree–Fock calculation of the equilibrium geometry of the isolated molecule gives values for bond lengths and valency angles in close agreement with experimental values. The calculation also reproduces the observed molecular conformation, with puckering parameters that agree well with those determined from the crystallographic study.