Streptonigrin alkaloids

Solanidine-type steroid alkaloids, synthesis and reactions 88MI6I. Streptonigrin, total syntheses of 84MI30. 

An example of the Stille reaction was used in preparing CD-ring model system 280 for the alkaloid streptonigrin 281 [99]. This was accomplished by the cross-coupling of 278 with 279. 

Methyltryptophan (92) has been shown to be a biosynthetic precursor of the antibiotic streptonigrin (93) in Streptomyces flocculus (J.K. Allen, K.D. Barrow and A.J. Jones, J.chem.Soc.Chem. Comm., 1979, 280). The antibiotic itself has been studied by other groups of chemists ( S.J. Gould and S.M. Weinreb, Fortschr.chem. Org.Naturst., 1982, 41, ofJ7). Another antibiotic, streptonlgrone (95), is metabolised hy Streptomyces sp. (A.J. Kelt, R.W. Rickards and J.-P. Wu, Antibiotics, 1985, 38, 516), but lavendamycin (94), a related alkaloid from S. lavendulae (T.W. Doyle et al.. Tetrahedron Letters, 1981, 4595), does not appear to be its natural precursor. Lavendamycin has been synthesised (A.S. Kende and F.H. Ebetino, Tetrahedron Letters, 1984, 923). 

Since the first isolation of the alkaloids containing quinolinequinone and quinolinequinoneimine units, phomazarin and calliactine, respectively, more than 30 alkaloids containing these units have been reported. Although the first two alkaloids were isolated in 1940, the remainder were isolated after 1980, except for streptonigrin and isophomazarin, which were isolated in 1959 and 1979, respectively. 

Contents E. HASLAM The Metabolism of Gallic Acid and Hexahydroxydi-phenic Acid in Higher Plants. — D. G. ROUX and D. FERREIRA The Direct Biomimetic Synthesis, Structure and Absolute Configuration of Angular and Linear Condensed Tannins. — ST. J. GOULD and ST. M. WEINREB Streptonigrin. — D. J. ROBINS The Pyrrolizidine Alkaloids. — J. W. DALY Alkaloids of Neotropical Poison Frogs (Dendrobatidae). 

Streptonigrin is an antibiotic produced by the actinomycetes, Streptomyces Jloaulus ATCC13257. Streptonigrin forms dark brown crystals and has shown strong cytocidal activity against various experimental animal tumors. The chemical structure of this antibiotic was determined by a combination of chemical degradation studies and physicochemical analyses [IJ.The total synthesis of this alkaloid was achieved [2],... 

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