ROTATIONAL INVESTIGATION OF TROPANE ALKALOIDS
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Date
2010
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Publisher
Ohio State University
Abstract
\begin{wrapfigure} [8] {r}{6.5cm} \vspace{-.5cm} \hspace*{-0cm} \epsfig{file=tropanes.eps} \end{wrapfigure} We report an investigation of the rotational spectrum of several tropane alkaloids using the new Balle-Flygare-type FT-MW spectrometero, in publication, 2010} built at the University of the Basque Country. The initial work focused on the azabicycles of tropinone, scopine and scopoline, vaporized using heating methods. For tropinoneo, \textit{Phys. Chem. Chem. Phys.},in press, 2010} the spectrum confirmed the presence of equatorial and axial conformers originated by the inversion of the \textit{N}-methyl group, with the tropane motif adopting a distorted chair configuration. The determination of substitution and effective structures for the two conformers included the $^{13}$C, $^{15}$N and $^{18}$O isotopomers observed in natural abundance. The structures revealed the flexibility and structural changes associated to the \textit{N}-methyl inversion, mostly a flattening at the nitrogen atom and a simultaneous rising of the carbonyl group in the axial form. The investigation of scopine gave an intense spectrum, but it was inconsistent with the structural models expected for this molecule. The carrier of the new spectrum was later identified as scopoline, generated \textit{in situ} by an intramolecular reaction at the moderate temperatures of the nozzle. A single conformation was detected for scopoline, with an ether bridge seriously distorting the tropane motif.
Description
Author Institution: Departamento de Qu\imica F\isica; Universidad del Pa\is Vasco, 48080 Bilbao, Spain; Departamento de Qu\imica F\isica y Qu\imica Inorganica; Universidad de Valladolid, 47011 Valladolid, Spain; Departamento de Qu\imica F\isica; Universidad del Pa\is Vasco, 48080 Bilbao, Spain; Institut fur Physikalische Chemie und Elektrochemie, Gottfried-Wilhelm-Leibniz-Universitat Hannover, Callinstra\ss e 3A; 30167 Hannover, Germany; Departamento de Qu\imica F\isica; Universidad del Pa\is Vasco, 48080 Bilbao, Spain