Tetranortriterpenoids and related substances. Part 19. Revised structures of atalantolide and atalantin, limonoids from the root bark of Atalantia monophylla correa (Rutaceae)

Abstract
Atalantolide and atalantin, two tetranortriterpenoids from the root bark of Atalantia monophylla Correa (Rutaceae), have been assigned the revised structures (5) and (13), respectively, on chemical and spectroscopic evidence. The diketone (9) obtained on oxidation of atalantolide undergoes ready enolisation.