title: NMR study of quinolizidine alkaloids: relative configurations, conformations.
abstract: Extracts of fruits and leaves of Connarus paniculatus afford six quinolizidine alkaloids which were identified as piptanthine, 18-epipiptanthine, ormosanine, homoormosanine, podopetaline (monohydrochloride) and homopodopetaline on the basis of high-field NMR studies. 1D and 2D NMR experiments provide complete assignments of the (1)H and (13)C spectra. In conjunction with detection of nuclear Overhauser effects (NOESY), these results allow detailed structure characterization including determination of relative configurations for the chiral sites and conformational analysis. Exchange phenomena involving nitrogen inversion were detected.
authors.affiliation: Institut de Chimie des Substances Naturelles, CNRS, avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France.
authors.forename: Phuong Mai
authors.initials: PM
authors.lastname: Le
authors.forename: Marie-Thérèse
authors.initials: MT
authors.lastname: Martin
authors.forename: Nguyen
authors.initials: N
authors.lastname: Van Hung
authors.forename: Daniel
authors.initials: D
authors.lastname: Guénard
authors.forename: Thierry
authors.initials: T
authors.lastname: Sévenet
authors.forename: Nicole
authors.initials: N
authors.lastname: Platzer
mesh_terms: D000470:Alkaloids / Q000737:chemistry*; D002247:Carbon Isotopes; D003903:Deuterium; D009682:Magnetic Resonance Spectroscopy / Q000379:methods* / Q000592:standards*; D008968:Molecular Conformation; D010936:Plant Extracts / Q000737:chemistry; D011522:Protons; D011807:Quinolizines / Q000737:chemistry*; D012015:Reference Standards
chemical_list: D000470:Alkaloids; D002247:Carbon Isotopes; D010936:Plant Extracts; D011522:Protons; D011807:Quinolizines; D003903:Deuterium