Ezomycin

An overview of various synthetic approaches to bicyclic nucleosides such as the octosyl acids and the ezomycins is presented. Details of the total synthesis of octosyl acids A and C are disclosed. 

The trans-fused perhydrofuropyran system is also encountered in the ezomycin group of nucleoside antibiotics (6,7). The structures of ezomycin Aj and Aj are shown in Figure 3 for comparison with the octosyl acids. 

ANTIBIOTICS NUCLEOSIDES AND NUCLEOTIDES. The naturally occurring nucleoside and nucleotide antibiotics exist as either the C- or N-glycosides (see Nucleic Acids). They include ezomycin Ai (Cjf.lUsNjOuS), ezomycin B (C26H39N7Oi7S), ezomycin C]... 

The naturally occurring C-nucleosides containing C-glycosyl linkages include ezomycins, showdomycin. oxazinomycin, pyrazomycin. and pyra-7olopyrimidine nucleosides. 

Ezomycins. Ezomycins are antifungal antibiotics produced by a strain of Streptomyces very similar to S. kitazawaensis. 

Hanessian, S, Liak, T J, Dixit, D M, Synthesis of trans-fused perhydrofuropyrans and related a-methylene lactones bicyclic ring-systems present in the ezomycins, the octosyl acids, and certain antitumor terpenoids, Carbohydr. Res., 88, C14-C19, 1981. 

O Scheme 3) abundant on glycoproteins or certain complex nucleoside antibiotics such as ezomycin [3]. 

Ogawa later published the synthesis of a 3-amino-3,4-dideoxyhexiu-onic acid in route to ezomycin [24]. In that account, a 1,6-anhydro epoxy sugar was reacted with sodium azide followed by antimony pentachloride to give methyl 3-azido-2-0-benzoyl-a-D-glucospyranoside. Oxidation of the primary alcohol was achieved with potassium permanganate, and reduction of the azide was accomplished with hydrogenation (Fig. 8). 

Ezomycin, effective against Sclerotinia and Botrytis spp., is obtained from Streptomyces cultures. In Japan it has been used against the stem rot of kidney bean (Sakata et a/., 1974). 

A. The Naturally Occurring Pyrimidine C-Nucleosides Pseudouridines and Ezomycins ... 

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