title: Crystal structure and computational study of 3,4-dihy-droxy-3-hy-droxy-methyl-9-methyl-6-methyl-idene-3a,4,5,6,6a,9,9a,9b-octa-hydro-azuleno[4,5-b]furan-2,8(3H,7H)-dione.
abstract: In the mol-ecule of title compound, C15H20O6, also known as cynarinin A, the cyclo-pentane ring having twist conformation and a γ-lactone ring assuming an envelope conformation are trans- and cis-fused, respectively, to a cyclo-heptane ring adopting a twist-chair conformation. In the crystal, O-H⋯O hydrogen bonds link neighbouring mol-ecules, forming a three-dimensional network. Theoretical calculations of the mol-ecular structure using the CNDO approximation and MOPAC PM3 geometry optimization are in satisfactory agreement with the results of the X-ray structure analysis.
authors: Department of Physics, Faculty of Arts and Sciences, Cumhuriyet University, 06532 Sivas, Turkey.
authors: Ísmail
authors: Í
authors: Çelik
authors: Department of Physics, Faculty of Sciences, Erciyes University, 38039 Kayseri, Turkey.
authors: Mehmet
authors: M
authors: Akkurt
authors: Department of Chemistry, Faculty of Science and Art, Gaziosmanpasa University, 60240 Tokat, Turkey.
authors: Hüseyin
authors: H
authors: Akşit
authors: Department of Chemistry, Faculty of Science and Art, Gaziosmanpasa University, 60240 Tokat, Turkey.
authors: Ramazan
authors: R
authors: Erenler
authors: Departamento Química Física y Analítica, Facultad de Química, Universidad Oviedo, C/ Julián Clavería, 8, 33006 Oviedo (Asturias), Spain.
authors: Santiago
authors: S
authors: García-Granda
keywords: CNDO; Centaurea polypodiifolia; HOMO; LUMO; PM3; crystal structure; cynarinin A; theoretical investigation