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Closed Access item Hydrogen-bond-mediated self-assembly of 26-membered diaza tetraester crowns of 3,5-disubstituted 1 h -pyrazole. Dimerization study in the solid state and in CDCl3 solution

Authors:Reviriego, Felipe
Navarro, Pilar
Arán, Vicente J.
Jimeno, M. Luisa
García-España, Enrique
Latorre, Julio
Yunta, María J. R.
Issue Date:2011
Publisher:American Chemical Society
Citation:Journal of Organic Chemistry 76: 8223- 8231 (2011)
Abstract:By using an improved synthetic method reported earlier, the cyclic stannoxanes obtained from RN-diethanolamine (R = Me, Bu) and dibutyltin oxide have been reacted with 1H-pyrazole-3,5-dicarbonyl dichloride to afford 26-membered diaza tetraester crowns (1, R = Me; 3, R = Bu) and 39-membered triaza hexaester crowns (2, R = Me; 4, R = Bu). The new structures were identified from their analytical and spectroscopic (1H and 13C NMR, FAB-MS, and/or ESI-MS) data. Both diaza tetraester crowns (1 and 3), containing two 1H-pyrazole units, self-assemble into dimeric species through the formation of four hydrogen bonds involving the two NH pyrazole groups and the two tertiary amine groups of both crowns, as proved by X-ray crystallography and NMR analysis. Preliminary NMR, ESI-MS, MALDI-TOF-MS, and molecular modeling studies suggest that, in CDCl3 solution, 1 interacts with ethyleneurea (ETU), affording 1:1, 2:1, and 2:2 1-ETU complexes. © 2011 American Chemical Society.
Identifiers:doi: 10.1021/jo2012835
issn: 0022-3263
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