title: DFT-GIAO study of aryltetralin lignan lactones: conformational analyses and chemical shifts calculations.
abstract: The conformational properties of polygamain and morelensin, two aryltetralin lignan lactones, have been investigated in both the gas-phase and chloroform solution using DFT calculations at the B3LYP/6-311G(d,p) level. Results indicate that the conformation of polygamain is very rigid. Thus, the conformational flexibility of its five-membered rings is considerably restricted as reflects the pseudorotational parameters of the corresponding envelope conformations. On the other hand, morelensin shows a notable conformational flexibility, which is mainly due to its two methoxy groups. Accordingly, 16 minimum energy conformations with relative energies smaller than 2.4 kcal/mol were detected. Furthermore, chemical shifts for 13C nuclei have been calculated using the GIAO method, results being compared with experimental data. A good agreement was found for both polygamain and morelensin.
authors.affiliation: Departament de Química, Escola Politècnica Superior, Universitat de Lleida, c/Jaume II n(o) 69, Lleida E-25001, Spain. jcasanovas@quimica.udl.es
authors.forename: Jordi
authors.initials: J
authors.lastname: Casanovas
authors.forename: Adriana M
authors.initials: AM
authors.lastname: Namba
authors.forename: R
authors.initials: R
authors.lastname: da Silva
authors.forename: Carlos
authors.initials: C
authors.lastname: Alemán
mesh_terms: D001572:Benzofurans / Q000737:chemistry*; D004149:Dioxoles / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D017705:Lignans / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D013764:Tetrahydronaphthalenes / Q000737:chemistry*
chemical_list: D001572:Benzofurans; D004149:Dioxoles; D007783:Lactones; D017705:Lignans; D013764:Tetrahydronaphthalenes; C499777:morelensin; C499776:polygamain; C095210:tetralin