(S)-7,8-Dihydro-8,8-dimethyl-2-oxo-2H,6H-benzo(1,2-b:5,4-b')dipyran-7-yl 3-methyl-2-butenoate 2-Butenoic acid, 3-methyl-, 7,8-dihydro-8,8-dimethyl-2-oxo-2H,6H-benzo(1,2-b:5,4-b')dipyran-7-yl ester, (S)- 5928-25-6 Decursin Decursinol angelate