2-Butenoic acid, 3-methyl-, 1a,2,3,7,8,8a,9,10,11a,11b-decahydro-1a-methyl- 9-methylene-5,10-dioxo-5H-3,6-methenofuro[2,3-f]oxireno[d]oxacycloundecin-8-yl ester 21899-50-3 Elephantin Germacra-1(10),11(13)-diene-12,14-dioic acid, 4,5.alpha.-epoxy-2.beta.,6.alpha.,8.alpha.-trihydroxy-, 12,6:14,2-dilactone, 3-methylcrotonate NSC102817