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1

School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Quai Ernest-Ansermet 30, CH-1211 Geneva 4, Switzerland

2

Department of Organic Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva 4, Switzerland

3

Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile





*

Author to whom correspondence should be addressed.



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 tropane alkaloids; Schizanthus; molecular configuration; Mosher’s esters; 3R,6R-3α-hydroxy-6b-senecioyloxytropane





Autor: Munir Humam 1, Tarik Shoul 1, Damien Jeannerat 2, Orlando Muñoz 3 and Philippe Christen 1,*

Fuente: http://mdpi.com/



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