Biogenesis of the Picralima Alkaloids

The co-occurrence in Picralima nitida of such a wide variety of structural types of indole alkaloids is of much interest from the point of view of their biogenesis. In this respect picraphylline (XXVIII) occupies a particularly important position, since all the congeneric alkaloids can be simply derived from it, or from its own biogenetic 

1 Xote, however, the co-occurreiice of echitamine, echitainidine (I9 hydroxy-I9,20-(liliydroakuammiciiie), and picririine in Alstonia scholaris. 

Budzikiewicz, J. M. Wilson, C. Djerassi, J. Levy, J. Le Men, and M. M. Janot, Tetrahedron 19, 1265 (1963) see also H. Budzikiewicz, C. Djerassi, and D. H. Williams, Structure Elucidation of Natural Products by Mass Spectrometry, Vol. I, Alkaloids, p. 133. Holden-Day, San Francisco, California, 1964. 

Alkaloids of Uncaria Oambier Roxb. and the Gambir Tannin. 539 

Continuing their investigations in this series the Chelsea group have reexamined the bases present in the leaves of M. speciosa Korth. and have isolated ten alkaloids, of which mitragynine (V R == OMe), now obtained crystalline for the first time (as its solvate with ethanol) (7-9), and speciofoline (stereoisomer of I) (10), have been reported earlier. Other known alkaloids include corynantheidine (V R = H) and ajmali-cine (VI), neither of which has previously been encountered in Mitragyna species, mitraphylline (VII), and isomitraphylline (VIII) (8, 9, 11). The four new bases obtained are speciophylline, C21H24N2O4 (mp 183°  

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