Structurally Diverse Meroterpenoids from a Marine-Derived <i>Aspergillus</i> sp. Fungus

Three new meroterpenoids, asperaustins A–C (1–3), and seven known analogues (4–10) were isolated from a marine-derived Aspergillus 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 (1) 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 (7) and precalidodehydroaustin (9) were determined by single-crystal X-ray diffraction analyses using Cu Kα radiation for the first time.