TERPENOIDS: X. PRE-SENEGENIN, A QUITE NORMAL TRITERPENOID

Abstract

Pre-senegenin has been obtained by a combination of oxidative and hydrolytic cleavage of the saponin, and has been shown to be a member of the normal and unrearranged oleanolic acid series: 2β,27-dihydroxy-23-carboxyoleanolic acid (XXII). On treatment with ethanolic hydrochloric acid it is converted quantitatively to a mixture of polygalic acid (XXI) and senegenin.Previous work (1) has shown that senegenin is a triterpenoid of empirical formula C30H45O6Cl with a 2β,3β-glycol system and a 4α-carboxyl group. A second carboxyl group is also present. It has now been found to be a member of the β-amyrin-oleanolic acid series in which a carbon atom at C14has migrated to C12with concomitant movement of the double bond to the C13—C14position, and that it has the structure (XX).