(E)-13-(2-Bromo­phen­yl)micheliolide

The title compound, C(21)H(23)BrO(3) [systematic name: (3E,3aS,6Z,9R,9aS,9bS)-3-(2-bromo­benzyl­idene)-9-hy­droxy-6,9-dimethyl-3,3a,4,5,7,8,9,9a-octa­hydro­azuleno[4,5-b]furan-2(9bH)-one] was prepared by the reaction of 1-bromo-2-iodo­benzene with micheliolide [systematic name: (3aS,R,9aS,9bS,Z)-9-hy­droxy-6,9-dimethyl-3-methyl­ene-3,3a,4,5,7,8,9,9a-octa­hydro­azuleno[4,5-b]furan-2(9bH)-one] under Heck reaction conditions. The title compound exhibits intra­molecular O—H⋯O hydrogen bonding between the hy­droxy group and the lactone ring O atom, forming a ring of graph-set motif S(6). The 2-bromo­phenyl group is trans to the lactone ring, indicating that this is the E isomer (geometry of the exocyclic C=C bond). The dihedral angle between the benzene ring of the 2-bromo­phenyl moiety and the mean plane of the lactone ring is 51.68 (7)°.