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NMR study of quinolizidine alkaloids: Relative configurations, conformations

Institut de Chimie des Substances Naturelles, CNRS, avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France.
Magnetic Resonance in Chemistry (Impact Factor: 1.18). 05/2005; 43(4):283-93. DOI: 10.1002/mrc.1554
Source: PubMed

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.

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    • "In the family Connaraceae, only six genera (Agelaea, Byrsocarpus, Cnestis, Connarus, Rourea, and Roureopsis) have been investigated for chemical composition and the major components have been quinolizidine alkaloids (Le et al., 2005), quinones (Aiyar et al., 1965; Ramiah et al., 1976a), triterpenes, coumarins, and flavonoids. Triterpenes have been found only in the genus Rourea (Zhang et al., 2008), coumarins in Byrsocarpus (Vickery & Vickery, 1980) and flavonoids in Agelaea (Kuwabara et al., 2003), Byrsocarpus (Ahmadu et al., 2007), Cnestis (Parvez & Rahman, 1992), Connarus (Aiyar et al., 1964; 1965; Ramiah et al., 1976b; Marcano et al., 1984), and Rourea (Jiang et al., 1990; Zhang et al., 2008; Kalegari, 2009). "
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