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Chirality and Numbering of Substituted Tropane Alkaloids
School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Quai Ernest-Ansermet 30, CH-1211 Geneva 4, Switzerland
Department of Organic Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva 4, Switzerland
Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile
* Author to whom correspondence should be addressed.
Received: 12 July 2011; in revised form: 16 August 2011 / Accepted: 17 August 2011 / Published: 25 August 2011
(This article belongs to the Special Issue 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 1H-NMR anisochrony (Δd) 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-6b-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.
Keywords: tropane alkaloids; Schizanthus; molecular configuration; Mosher’s esters; (3R,6R)-3α-hydroxy-6b-senecioyloxytropane
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MDPI and ACS Style
Humam, M.; Shoul, T.; Jeannerat, D.; Muñoz, O.; Christen, P. Chirality and Numbering of Substituted Tropane Alkaloids. Molecules 2011, 16, 7199-7209.
Humam M, Shoul T, Jeannerat D, Muñoz O, Christen P. Chirality and Numbering of Substituted Tropane Alkaloids. Molecules. 2011; 16(9):7199-7209.
Humam, Munir; Shoul, Tarik; Jeannerat, Damien; Muñoz, Orlando; Christen, Philippe. 2011. "Chirality and Numbering of Substituted Tropane Alkaloids." Molecules 16, no. 9: 7199-7209.