Acta Cryst. (2008). E64, o585-o586  [ doi:10.1107/S1600536807062812 ]

A second polymorph of -arteether

J. P. Jasinski, R. J. Butcher, H. S. Yathirajan, B. Narayana and T. V. Sreevidya

Abstract: The crystal structure of the title compound, C₁₇H₂₈O₅, reported here is a polymorph of the structure first reported by El-Feraly, Al-Yahya, Orabi, McPhail & McPhail [J. Nat. Prod. (1992). 55, 878-883]. It is a derivative of the antimalaria compound artemisinin and consists primarily of three substituted ring systems fused together. A cyclohexane ring (distorted chair conformation) fused to a tetrahydropyran group (distorted chair) is adjacent to an oxacycloheptane unit containing an endo-peroxide bridge, giving the molecule its particular three-dimensional arrangement. The crystal packing is stabilized by intermolecular C-HO interactions between an O atom from the endo-peroxide bridge and H atoms from both the cyclohexane and seven-membered oxacycloheptane fused rings, as well as between an O atom and H atom from adjacent tetrahydropyran rings. The two polymorphs have the same space group and similar cell parameters for the a and b axes, but significantly different values for the c axis.

Online 13 February 2008

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