Pithomyces chartarum

Pioneering studies on hypervalent iodine-induced reactions toward total syntheses of several natural products had been reported from the 1970s to the early 1980s. That is, Kishi and co-workers accomplished the total synthesis of sporidesmin A (120), which is a toxic metabolite of Pithomyces chartarum, by PIDA-mediated cyclization of tryptamine derivative 121, but, the yield of tricyclic compound 122 was only 30% [85] (Scheme 1). 

Hyalodendron sp. (fungus) Penicillium turbatum Pithomyces chartarum ... 

Sporidesmin is a naturally occurring polycyclic disulfane that contains the piperazinedione ring shown in Table 6. The corresponding trisulfane has been termed sporidesmin E. It has been obtained by extraction of Pithomyces chartarum followed by LC on silica gel. From the same organism, sporidesmin G, the corresponding tetrasulfane, has been obtained. These compounds are also biologically active. 

When using conventional geometry instruments, HV scan method combined with high resolution may occasionally be effective. In this way. Das and co-workers [213a,b] studied the components of pithamycolide fractions of extracts from Pithomyces chartarum cultures. The elucidation of structure of dipeptide has been done by this method. The measurements of the main peaks obtained in El under high-resolution conditions furnished the results shown in Table 20, and these enabled a true family tree to be generated when combined with the determination of their precursor ions (by HV scan) (Table 21). 

Figure 62. Proposed structure for the cyclic depsipeptide isolated in Pithomyces chartarum.

Sporidesmin B, one of the minor toxic metabolites of Pithomyces chartarum, was obtained (Scheme 6) by reducing the intermediate (60a) to (60b) and then by a sequence of steps which parallel those used for sporidesmin A. 

Pythomycolide (1198), a cyclodepsipeptide of the pasture fungus Pithomyces chartarum, has an unusual structure in bearing two p-substituted residues, thus forming a 17-membered ring. It is known to bind strongly to Na" and Ca " ions in organic solvents. The total synthesis was conducted in 1994 by Le Quesne et al. on the macrolactonization of compound 1197 to the natural product pithomycolide (1198) (Scheme 15.1) 778, 779). 

Fusarium graminearum Rhizoctonia leguminicola Pithomyces chartarum Penicillium rubrum Penicillium expansum Penicillium citrinum Penicillium cyclopium... 

Sporidesmins are toxic metabolites of Pithomyces chartarum, and the cause of serious hepatoxic disease in sheep, J. W. Ronaldson, A. Taylor, E. P. White and R. J. Abraham, J. Chem. Soc., 3172 (1963) S. Safe and A. Taylor, J. Chem. Soc. Perkin I, 472 (1972) and references cited therein. 

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