title: Chirality and numbering of substituted tropane alkaloids.
abstract: The strict application of IUPAC rules for the numbering of tropane alkaloids is not always applied by authors and there is hence a lot of confusion in the literature. In most cases, the notation of 3, 6/7-disubstituted derivatives has been chosen arbitrarily, based on NMR and MS data, without taking into account the absolute configuration of these two carbons. This paper discusses the problem and the relevance of CD and NMR to determine molecular configurations. We report on the use of (1)H-NMR anisochrony (Δδ) induced by the Mosher's chiral auxiliary reagents (R)-(-)- and (S)-(+)-α-methoxy-α-trifluoromethyl-phenylacetyl chlorides (MTPA-Cl), to determine the absolute configuration of (3R,6R)-3α-hydroxy-6β-senecioyloxytropane, a disubstituted tropane alkaloid isolated from the aerial parts of Schizanthus grahamii (Solanaceae). These analytical tools should help future works in correctly assigning the configuration of additional 3, 6/7 disubstituted tropane derivatives.
authors.affiliation: School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Quai Ernest-Ansermet 30, CH-1211 Geneva 4, Switzerland. munir_humam@hotmail.com
authors.forename: Munir
authors.initials: M
authors.lastname: Humam
authors.forename: Tarik
authors.initials: T
authors.lastname: Shoul
authors.forename: Damien
authors.initials: D
authors.lastname: Jeannerat
authors.forename: Orlando
authors.initials: O
authors.lastname: Muñoz
authors.forename: Philippe
authors.initials: P
authors.lastname: Christen
mesh_terms: D016880:Anisotropy; D002942:Circular Dichroism; D004952:Esters; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D015394:Molecular Structure; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry; D019657:Solanaceae / Q000737:chemistry; D013237:Stereoisomerism; D009626:Terminology as Topic; D014326:Tropanes / Q000737:chemistry*
chemical_list: D004952:Esters; D010936:Plant Extracts; D014326:Tropanes