The unsaturated P-pyrone antibiotic'cortalcerone (2-hydroxy-6H-3-pyrone-2- carboxaldehyde hydrate, 1) was first prepared from aqueous macerates of mycelia from the basidiomycete Corticium caeruleum, by selective solubilization and precip itation followed by repeated silica-gel column chromatography. Subsequent studies2T3 showed that cortalcerone is derived from o-glucose through a multi-step pathway involving oxidation of ...