Isolation and structure determination of cotonefuran, an induced antifungal dibenzofuran from Cotoneaster lactea W.W.Sm.

Abstract

An antifungal compound, cotonefuran, has been isolated from necrotic wood of a fungal-infected specimen of Cotoneaster lactea W.W.Sm. (Rosaceae). Spectroscopic evidence demonstrates that cotonefuran is a trimethoxydibenzofurandiol which is trisubstituted in one aromatic ring and disubstituted in the other. Comparison of the ¹H n.m.r. spectrum with the ¹H n.m.r. spectra of suitable model dibenzofurans provided some information on the positioning of the substituents, but an X-ray analysis was necessary for a full structural elucidation. Cotonefuran was thus shown to be 3,4,6-trimethoxydibenzofuran-2,7-diol (9). The compound was not found in healthy sapwood and is probably a phytoalexin.