摘要
Palisadin B,a brominated sesquiterpenoid, was isolated from the marine alga genus Laurencia Karlae Zhang et Xia collected from the Nansha Islands of the South China Sea. The structure was examined by MS and NMR spectra and confirmed by X-ray diffraction analysis.C_(15) H_(24) Br_2O, Mr=380.18, tetragonal,P4_12_12, a= 10. 812(3) ,c=27. 436(7),V=3027. 1, Z=8, D_c= 1. 948Mg. m￣(-3) ,μ(MoKa) = 61. 81 cm￣(-1), F(000) =1900,T=296K,final R=0. 050 for 1082 observed reflections. The molecule is composed of a cyclohexane ring fused with a seven-membered cyclic ether, and the latter exhibits a twist boat conformation.The molecules in the crystal lattice are held together by van der Waals forces (m. p.367-368K). Bond lengths and angles are internally consistent and the van der Waals interactions are normal.
