Synonyms: Spiro[benzo[4,5]cyclodeca[1,2-b]furan-12(2H),2'-oxiran]-2-one,8,9,11,13-tetrakis(acetyloxy)-4-chlorotetradecahydro-13a-hydroxy-1,8a-dimethyl-5-methylene-,[1R-(1R*,3aR*,4S*,8S*,8aS*,9S*,11R*,12R*,12aS*,13S*,13aR*)]-; (+)-GemmacolideC; Gemmacolide C; Robustolide H