Conversion of α- and β-amyrin into ursolic and oleanolic acids respectively. A synthesis of oleanolic acid

Abstract

β-Amyrin has been converted into 3β-acetoxy-13-hydroxyoleanane. Photolysis of the nitrite of this alcohol and further standard transformations gave oleanolic acid lactone acetate and thence oleanolic acid. This conversion of β-amyrin into oleanolic acid represents, in the formal sense, a total synthesis of the latter.

By a similar series of reactions ursolic acid has been obtained from α-amyrin.