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Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Conformational Analysis and Absolute Configuration of Axially Chiral 1-Aryl and 1,3-Bisaryl-xanthines
Michele Mancinelli1, Sofia Perticarari1, Luca Prati1
1Department of Industrial Chemistry "Toso Montanari", University of Bologna , Viale Risorgimento 4, 40136 Bologna, Italy.
Abstract:
The xanthine scaffold is known to be the forefather of a class of biological active molecules. Xanthine is a planar framework in which an aryl substituent linked in the 1 or 3 position is driven out of the xanthine plane because of the steric hindrance exerted by the two carbonyls. This work analyses the stereodynamics of some 1-aryl and 1,3-bisaryl-xanthines and describes the steric requirements needed to produce stable heteroaromatic atropisomers or diastereoisomers, with one or two N-Csp2 stereogenic axes. The N-C racemization barrier was found to be bigger than 25 kcal/mol. The absolute configurations of the novel atropisomers has been assigned using TD-DFT simulation of ECD spectra.
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