The alkaloids of Prosopis and Cassia species

Prosopine (44a), prosopinine (44b), isoprosopinine A (44c), isoprosopinine B (44d), prosophylline (44e), prosofrine (44f), and prosofrinine (44g) are metabolites of Prosopis africana (Q.K.-Huu et al., Bull.Soc.cliim. Beiges, 1972, 81, 425 443). Two related allcaloids prosopinone and allcaloid D occur in Cassia carnaval (D. LytVigoe et al., Anales Asoc. Quim.Argentina, 1972, 60, 317), their structures are not totally secure but are lilcely to be (44h) and 44)1) respectively. 

The above structural assignments owe much to chemical degradations and to H n.m.r. spectroscopy, but stereoselective synthesis of (-)-deoxoprosopinine (45, 6gH), and (-)-deoxoprosophylline (45, 6a-H) derivatives of the corresponding natural products, and also of prosafrinine have now been reported (Y. Saitoh et al, Tetrahedron Letters, 1980, 21, 75 Bull.chem.Soc.(Japan), 1981, 54, 233 M. Natsume and M. Ogawa, Heterocycles, 1980, 14, 615). Other syntheses include that of ( ) isoprosopinine B (and also of (+)-desoxoprospinine) (A.B. Holmes et al., Chem.Comm., 1985, 37) Prosophylline has also been synthesised idem. ibid., 1981, 16, 973). 

W-Methylcassine occurs in several Prosopis species (I.B. Giarinetto, J.L. Cabrera and H.R. Juliani, J.nat.Prod., 1980, 43, 632), while isocassine (47) spectalinine (48) and iso-6-carnavaline (49) are obtained from C. spectablis (I. Christofidis, A. Welter and J. Jadot, Tetrahedron, 1977, 33, 977 3005). Related compounds occur in Prosopis julifora (V.U. Ahmad, A. Basha and W. Haque, Z. Naturforsch, 1978, 

these are called juliforidine, juliflorine and juliforicine. The first has been allocated structure (50) without stereochemical qualification. 

Melochlnine (51,R=H) from the leaves of Meloohia pyramidata has been converted into the same product (52 ) as that 

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