A new phthalide derivative, xylarphthalide A (1), along with two known compounds (-)-5-carboxylmellein (2) and (-)-5-methylmellein (3), were isolated from the endophytic fungus Xylaria sp. GDG-102 cultured from the Chinese medicinal plant Sophora tonkinensis. Their structures were identified by MS and NMR experiments, and the absolute configuration of 1 was further confirmed by single-crystal X-ray diffraction analysis. Compound 1-3 showed antibacterial activities against Bacillus megaterium, Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Shigella dysenteriae with MIC values of 12.5-25 μg/mL.

A highly diastereoselective and practical biomimetic total synthesis of (±)-basiliolide B has been achieved through the study of the two proposed biosynthetic pathways (O-methylation and O-acylation) for the unprecedented 7-methoxy-4,5-dihydro-3H-oxepin-2-one (C ring). The synthesis featured a cyclopropanation/ring opening strategy for establishing the stereogenic centers at C8 and C9, a biomimetic 2-pyrone Diels-Alder cycloaddition for the synthesis of the ABD ring system, and finally a highly efficient biomimetic intramolecular O-acylation for the C ring formation. This result provides an important perspective on the biosynthetic origin of the unprecedented 7-membered acyl ketene acetal moiety of the C ring.

A small focussed library of basiliolides including basiliolide A1, basiliolide A2, basiliolide C, and their structural analogues have been prepared for structure–activity‐relationship studies. The synthesis features a cyclopropanation/ring‐opening strategy to establish the C‐8 stereogenic centre by using the cyclopropanation substrate with the appropriate alkene geometry; an IMDA (intramolecular Diels–Alder) reaction to construct the seco acid derivatives; and a biomimetic O‐acylation to form the unprecedented seven‐membered acyl ketene acetal ring. The des‐D‐ring analogues were prepared by an IMDA/decarboxylation strategy. Moreover, an asymmetric catalytic cyclopropanation reaction has been developed; this provided an optically enriched intermediate for asymmetric synthesis.