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Wortmannin (1) and its 11-desacetoxy derivative 2 are highly susceptible to nucleophiles, which limits the possibilities of transformation. Masking the furan ring by a new method allowed selective transformations with various reagents.

Introduction of the corticoid side chain into position 17 of wortmannin (1) and its 11-desacetoxy derivative (2) has been achieved by masking the furan ring.

The structure of 11-desacetoxy-wortmannin (3), a new antiinflammatory metabolite of the fungus Penicillium funiculosum THOM, has been elucidated by physico-chemical methods and chemical correlation with wortmannin (1).

Wortmannin (1) and its 11-desacetoxy derivative 2 are highly susceptible to nucleophiles, which limits the possibilities of transformation. Masking the furan ring by a new method allowed selective transformations with various reagents.

The crystal structure and absolute configuration of the fungal metabolite Wortmannin, isolated from Myrothecium roridium Tode ex Fries, have been determined.

Degradation of the fungal metabolite, wortmannin, by dilute mineral acid yields, inter alia, an acid C18H16O5 to which structure (Ia) is assigned from the spectroscopic properties of its derivatives. The assigned structure (Ia) is supported by dehydrogenation of the methyl ether methyl ester (Id) to methyl 2,3-dihydro-10-methoxy-6-methyl-3-oxo-1H-cyclopenta[7,8]naphtho[2,3-b]furan-7-carboxylate (VII), a previously described degradation product of the fungal metabolite, viridin (VI; X = O).

Structure (II) is proposed for the fungal metabolite, wortmannin. The absolute stereochemistry is deduced except for that at C-1, which remains undefined. The structure of the previously described acid, C21H22O7, obtained by acidic degradation, is determined, together with structures of the products of hydrolysis by potassium carbonate and by potassium hydrogen carbonate.

Wortmannin is an antibiotic isolated from a culture of Penicillium wortmanni Klocker. It is not antibacterial. In its antifungal properties it is remarkably specific; of thirty-eight fungal species examined in spore germination tests, twenty-one were unaffected by 100 μg./ml., whereas five species (Botrytis allii, B. cinerea, B. fabae, Cladosporium herbarum and Rhizopus stolonifer) were inhibited by concentrations between 0·4 and 3·2 μg./ml. Wortmannin is a neutral substance, m.p. 240° C, very unstable in aqueous solutions of pH 3–8. It causes a characteristic spiral waving of germ-tubes of B. allii, easily distinguishable from that caused by griseofulvin.