Virgatolides A-C, Benzannulated Spiroketals from the Plant Endophytic Fungus Pestalotiopsis virgatula

Virgatolides A-C (1-3), unique metabolites with a 3',4',5',6'-tetrahydrospiro[chroman-2,2'-pyran] core, were Isolated from cultures of the plant endophytic fungus Pestalotlopsis virgatula. Compounds 1-3 possess two previously undescribed skeletons originating from a benzannulated 6,6-spiroketal and one (2 and 3) and two (1) gamma-lactone units, respectively. The structure of 1 was secured by X-ray crystallography.