Rogiolol Acetate: A Novel β‐Chamigrene‐Type Sesquiterpene Isolated from a Marine Sponge

The marine sponge Spongia zimocca SCHMIDT, 1862, collected in front of the torrent II Rogiolo, south of Livorno, contains the sesquiterpene rogiolol acetate (= (+)‐(2R,3S,6R,8R,9R)‐2,8‐dibromo‐9‐chloro‐1,1,9‐trimethyl‐5‐methylidenespiro[5.5]undec‐3‐yl acetate; (+)‐3a), which represents the first chamigrane isolated from a sponge. Although compounds of this class are common in red seaweeds of the genus Laurencia, and our sponge actually contains 9‐bromochamigrene and a variety of other metabolites of nearby growing Laurencia sp., (+)‐3a is unique to our sponge.