Two pairs of enantiomeric α-pyrone dimers from the endophytic fungus Phoma sp. YN02-P-3

(±) Phomones A (1) and B (2), two pairs of novel enantiomeric α-pyrone dimers from the endophytic fungus Phoma sp. YN02-P-3 are reported. Compounds 1 and 2 are the first examples of 6-α,β-unsaturated ester-2-pyrone dimers, and compound 1 possesses a novel 6/4/5/6 tetracyclic ring system. Their structures and stereochemistry were determined by the analysis of extensive spectroscopic data, ECD calculations and single-crystal X-ray diffraction data.