New Furano‐sesquiterpenoids from Mediterranean Sponges

A mixture of sponges of the East Pyrenean Mediterranean is shown to contain the known sponge products longifolin (1), avarol ((+)‐3), and avarone (4) and the terrestrial‐plant product sesquirosefuran (2), besides to the new furano‐sesquiterpenoids tavacfuran (= 3‐methyl‐2‐[(3′Z)‐3′‐methyl‐4″‐methyl‐2″‐furyl‐3′‐butenyl]furan; (5) and tavacpallescensin (= 5,10‐dihydro‐6,9‐dimethyl‐4H‐benzo[5,6]cyclohepta[1,2‐b]furan; 6) and the new furano‐butenolide sesquiterpenoids tavacbutenolide‐1 (= (±‐4‐ethoxy‐2‐methyl‐4‐)[(2′E)‐2′‐methyl‐4′‐(3″‐methyl‐2″‐furyl)‐2′‐butenyl]‐2‐buten‐4‐olide; (±)‐7) and tavacbutenolide‐2 (= (±)‐4‐ethoxy‐3‐methyl‐4‐[2′E)‐3′‐methyl‐4′‐(4″‐methyl‐2″‐furyl)‐2′‐butenyl]‐2‐buten‐4‐olide; (±)‐8). Structural assignments are based on NMR data and on the synthesis of the (E)‐isomer of 5. The sponge Dysidea tupha of the same area is also shown to contain the two sesquiterpenoids ent‐furodysinin ((−)‐14), which is enantiomeric to a product of a Dysidea sp. of Australian waters, and tuphabutenolide ((+)‐15).