title: A P212121 polymorph of (+)-clusianone.
abstract: The title compound, C33H42O4 [systematic name: (1S,5S,7R)-3-benzoyl-4-hy-droxy-8,8-dimethyl-1,5,7-tris-(3-methyl-but-2--enyl)bi-cyclo-[3.3.1]nona-3-ene-2,9-dione], has a central bi-cyclo-[3.3.1]nonane-2,4,9-trione surrounded by tetra-prenyl-ated and benzoyl groups. The compound was recrystallized several times in methanol using both a slow evaporation method and with a crystal-seeding technique. This subsequently produced diffraction-quality crystals which crystallize in the ortho-rhom-bic space group P212121, in contrast to a previous report of a structure determination in the Pna21 space group [McCandlish et al. (1976 ▶). Acta Cryst. B32, 1793-1801]. The title compound has a melting point of 365-366 K, and a specific rotation [α](20) value of +51.94°. A strong intra-molecular O-H⋯O hydrogen bond is noted. In the crystal, mol-ecules are assembled in the ab plane by weak C-H⋯O inter-actions.
authors.affiliation: Center for Natural and Medicinal Product Research, School of Pharmacy, Faculty of Science, University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor, Malaysia.
authors.forename: Sree
authors.initials: S
authors.lastname: Vaneesa Nagalingam
authors.affiliation: Center for Natural and Medicinal Product Research, School of Pharmacy, Faculty of Science, University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor, Malaysia.
authors.forename: Janet
authors.initials: J
authors.lastname: Wong Pik Ching
authors.affiliation: School of Chemical Sciences and Food Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Malaysia.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Khaled Bin Break
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Malaysia.
authors.forename: M Ibrahim M
authors.initials: MI
authors.lastname: Tahir
authors.affiliation: Center for Natural and Medicinal Product Research, School of Pharmacy, Faculty of Science, University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor, Malaysia.
authors.forename: Teng-Jin
authors.initials: TJ
authors.lastname: Khoo