Structurally Diverse Meroterpenoids from a Marine-Derived sp. Fungus.

Three new meroterpenoids, asperaustins A-C (-), and seven known analogues (-) were isolated from a marine-derived sp. fungus. The structures and absolute configurations of these new compounds were unequivocally determined by extensive spectroscopic analyses and single-crystal X-ray diffraction analyses. Asperaustin A () possesses an unusual spiro[4.5]deca-3,6-dien-2-one moiety with a unique 5/6/6/6/5 pentacyclic skeleton. The absolute configurations of austinoneol A () and precalidodehydroaustin () were determined by single-crystal X-ray diffraction analyses using Cu Kα radiation for the first time.