Synonyms: 2-Butenoicacid, 3-methyl-, 2,3,5,7a-tetrahydro-7-[[(3-methyl-1-oxo-2-butenyl)oxy]methyl]-1H-pyrrolizin-1-ylester, (1R-trans)-; Retronecine, bis(3-methylcrotonate) (ester) (8CI);Retronecine, disenecioyl- (6CI); Crotonic acid, 3-methyl-, diester withretronecine (8CI); Retronecine senecioate ester