Triterpenoids from Entandrophragma cylindricum Sprague. Part I. Structures of sapelins A and B

Abstract

Two triterpenes, sapelins A and B, have been isolated from commercial sapele (Entandrophragma cylindricum) They are shown to have the structures (I) and (X), respectively, on the basis of chemical and spectroscopic evidence and correlation with bourjotinolone A. The stereochemistry of the dihydroxyoxepan, a novel modification of the triterpene side chain, in sapelin B is deduced from biogenetic considerations.