Metabolites of the higher fungi. Part 29. Maldoxin, maldoxone, dihydromaldoxin, isodihydromaldoxin and dechlorodihydromaldoxin. A spirocyclohexadienone, a depsidone and three diphenyl ethers: keys in the depsidone biosynthetic pathway from a member of the fungus genus Xylaria

Abstract

2-(3′-Chloro-2′-hydroxy-4′-methoxy-6′-methoxycarbonylphenoxy)-6-hydroxy-4-methylbenzoic acid (dihydromaldoxin 1), 2-(3′-Chloro-4′-hydroxy-2′-methoxy-6′-methoxycarbonylphenoxy)-6-hydroxy-4-methylbenzoic acid (isodihydromaldoxin 2), dechlorodihydromaldoxin 3, a new chlorinated depsidone (maldoxone 4) and a new spirocyclohexadienone (maldoxin 5) have been isolated from the culture medium of an as yet unidentified Xylaria species. The structures have been determined by physical and chemical methods and the positions of the substituents in dihydromaldoxin 1 have been confirmed by a single crystal X-ray structure determination. Their role in the grisan–depsidone biosynthetic pathway is discussed.