The structure elucidation of a new phytoalexin, isolated from diseased mulberry leaves and designated as chalcomoracin, is described. The compound is regarded biogenetically as a Diels–Alderadduct of a chalcone, isolated newly from diseased mulberry shoots, and a substituted 2-phenylbenzofuran.
Conclusive evidence is presented supporting structures and for two natural Diels-Alder adducts isolated from mulberry and designated as kuwanon G (albanin F, moracenin B) and Kuwanon H (albanin G, Moracenin A).