(E)-13-(4-Aminophenyl)parthenolide

0.027; wR factor = 0.070; data-to-parameter ratio = 14.1. The title compound, C21H25NO3 [systematic name: (3aS,9aR,10aR,10bS,E)-3-[(E)-4-(4-aminobenzylidene)-6,9a-dimethyl-3a,4,5,8,9,9a,10a,10b-octahydrooxireno[20,30:9,10]-cyclodeca[1,2-b]furan-2(3H)-one] was obtained from the reaction of parthenolide [synonym: 4,5-epoxygermacra-1(10),11(13)-dieno-12,6-lactone] with 4-iodoaniline under Heck reaction conditions. It was identified as the E-isomer (conformation about the exocyclic methylidene C C bond; the conformation about the C C bond in the ten-membered ring is also E). The molecule is built up from fused ten-, five- (lactone) and three-membered (epoxide) rings with a 4-aminophenyl group as a substituent. The ten-membered ring displays an approximate chair–chair conformation, while the lactone ring has an envelop