title: Crystal structure of 3,4a,7,7,10a-penta-methyl-3-vinyl-dodeca-hydro-1H-benzo[f]chromen-9-ol isolated fromSideritis perfoliata.
abstract: The asymmetric unit of the title compound, C20H34O2, contains two crystallographically independent mol-ecules (1 and 2) with similar conformations. In both mol-ecules, the cyclo-hexane rings adopt a chair conformation, while the oxane rings are also puckered. In the crystal, O-H⋯O hydrogen bonds connect adjacent mol-ecules, formingC(6) helical chains located around a 21screw axis and running along the crystallographicaaxis. The packing of these chains is governed only by van der Waals inter-actions. Semi-empiricalPM3quantum chemical calculations are in a satisfactory agreement with the structural results of the X-ray structure analysis. The absolute structure was indeterminate in the present experiment.
authors.affiliation: Department of Physics, Faculty of Sciences, Cumhuriyet University, 58140 Sivas, Turkey.
authors.forename: Ísmail
authors.initials: Í
authors.lastname: Çelik
authors.affiliation: Department of Physics, Faculty of Arts and Sciences, Sinop University, 57010 Sinop, Turkey.
authors.forename: Cem Cüneyt
authors.initials: CC
authors.lastname: Ersanlı
authors.affiliation: Department of Physics, Faculty of Sciences, Erciyes University, 38039 Kayseri, Turkey.
authors.forename: Rahmi
authors.initials: R
authors.lastname: Köseoğlu
authors.affiliation: Department of Chemistry, Faculty of Arts and Sciences, Gaziosmanpaşa University, 60240 Tokat, Turkey.
authors.forename: Hüseyin
authors.initials: H
authors.lastname: Akşit
authors.affiliation: Department of Chemistry, Faculty of Arts and Sciences, Gaziosmanpaşa University, 60240 Tokat, Turkey.
authors.forename: Ramazan
authors.initials: R
authors.lastname: Erenler
authors.affiliation: Department of Chemistry, Faculty of Natural Sciences, Çankırı Karatekin University, 18100 Çankırı, Turkey.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Demirtaş
authors.affiliation: Department of Physics, Faculty of Sciences, Erciyes University, 38039 Kayseri, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Akkurt
keywords: HOMO; LUMO; crystal structure; cyclo­hexane ring; semi-empirical PM3 method