Metabolites of the higher fungi. Part 33. Grammicin, a novel bicyclic C7H6O4 furanopyranol from the fungus Xylaria grammica (Mont.) Fr.

Grammicin 1 from Xylaria grammica is identified as 4-hydroxy-4H-furo[2,3-b]pyran-2(7aH)-one by chemical and physical methods. 4-Oxo-4H-pyran-3-acetic acid (gamma -pyrone-3-acetic acid) 2 is a co-metabolite and the conversion of 1 into 2 is discussed.