Azafluorenones from Oxandra cf. major and biogenetic considerations

Abstract The stem bark of Oxandra cf. major , which contains large amounts of 7,7′-bisdehydroaporphine alkaloids, has also yielded three commonplace steroids, reticuline, four known aporphinoids and the new azafluorenones darienine, macondine and ursuline. Three biogenetic hypotheses are discussed in the light of the structures of the azafluorenones found to date in the Annonaceae.