Brasilamides A-D: Sesquiterpenoids from the Plant Endophytic Fungus Paraconiothyrium brasiliense

New tricyclic sesquiterpenoids brasilamides A–D (1–4) and the known pinthunamide (5) have been isolated from cultures of the plant endophytic fungus Paraconiothyrium brasiliense Verkley. Their structures were elucidated primarily by NMR spectroscopy, and the structure of 1 was further confirmed by X‐ray crystallography. The absolute configuration of the C‐5 tertiary alcohol in 2 was assigned by analogy to 1 and confirmed by observing the circular dichroism of in situ generated [Rh2(OCOCF3)4] complex. Compounds 2–4 showed modest inhibitory effects on HIV‐1 replication in C8166 cells. Compounds 1 and 2 possess an unprecedented4‐oxatricyclo‐[3.3.1.02,7]nonane skeleton. Paraconiothyrium brasiliense produced four new tricyclic sesquiterpenoids namedbrasilamides A–D (1–4); compounds 1 and 2 possess an unprecedented 4‐oxatricyclo[3.3.1.02,7]nonane skeleton. Compounds 2–4 showed modest inhibitory effects on HIV‐1 replication in C8166 cells.