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Acta Cryst. (2013). E69, o408-o409
[ doi:10.1107/S1600536813004017 ]


N. Romero, D. Gnecco, J. Terán and S. Bernès

Abstract: The title bis-piperidine, C26H28N2O3, was unexpectedly obtained via a dimerization mechanism promoted by acetic acid when performing the Dieckmann cyclization of a chiral amido ester. The S,S configuration was assigned by reference to the enantiomerically pure starting material. In the molecule, two core heterocycles are linked by a [sigma] bond. One ring includes a keto-enol group, while the other presents an enone functionality. Both rings present a conformation intermediate between envelope and screw-boat, and the dihedral angle between the mean planes passing through the rings [48.9 (1)°] is large enough to avoid hindrance between ring substituents. The enol tautomeric form in one ring favors the formation of strong intermolecular O-H...O=C hydrogen bonds. The resulting one-dimensional supramolecular structure features single-stranded helices running along the 21 screw axis parallel to [100].

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