NMR study of quinolizidine alkaloids: relative configurations, conformations.
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.
Le
Phuong Mai
PM
Institut de Chimie des Substances Naturelles, CNRS, avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France.
Martin
Marie-Thérèse
MT
Van Hung
Nguyen
N
Guénard
Daniel
D
Sévenet
Thierry
T
Platzer
Nicole
N
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
D000470:Alkaloids; D002247:Carbon Isotopes; D010936:Plant Extracts; D011522:Protons; D011807:Quinolizines; D003903:Deuterium