Synonyms: 2-Butenoicacid, 2-methyl-,1,2,3,4,6,7,8,8a-octahydro-1,8a-dimethyl-7-(1-methylethenyl)-6-oxo-2-naphthalenylester, [1R-[1a,2b(Z),7b,8aa]]-; Eremophila-9,11-dien-8-one, 3a-hydroxy-, 2-methylcrotonate, (Z)- (8CI); Petasin(6CI,7CI); Crotonic acid, 2-methyl-, ester with 3a-hydroxy-eremophila-9,11-dien-8-one, (Z)- (8CI);(+)-Petasin; Petaforce