Diplofuranones A and B, two further new 4-monosubstituted 2(3H)-dihydrofuranones produced byDiplodia corticola, a fungus pathogen of cork oak

Two new 4-monosubstituted 2(3H)-dihydrofuranones, named diplofuranones A and B, were
isolated from liquid cultures ofDiplodiacorticola, a plant pathogenic fungus causing a canker
disease of cork oak (QuercussuberL.). The same fungus also produces several metabolites such
as the diplopyrone, the (3S,4R)-trans- and the (3R,4R)-cis-4-hydroxymellein, the sapinofuranone
B and its (S,S)-enantiomer, the well known sphaeropsidins A-C, and the diplobifuranylones A
and B. The diplofuranones A and B were characterised, using spectroscopic (essentially NMR
and MS techniques) methods, as the 4-[(1E,3E)-5-hydroxyhexadienyl]butan-4-olide and its
corresponding 3,4-dihydro side chain derivative. The stereochemistry of the stereogenic
secondary hydroxylated carbon of the side chain of diplofuranone A was determined by
application of Mosher’s method and proved to be R. Diplofuranone A tested at 0.2 mg mL-1on
non-host plant did not show phytotoxic activity.