2-Propenoic acid, 2-methyl-, 2,3,3a,4,4a,5,7a,8,9,9a-decahydro-4a,8-dimethyl-3-methylene-2,5-dioxoazuleno(6,5-b)furan-4-yl ester, (3aR-(3aalpha,4alpha,4abeta,7aalpha,8alpha,9aalpha))- 68798-43-6 Helenalin methacrylate