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

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

The Journal of organic chemistry (2011-09-14)
Felipe Reviriego, Pilar Navarro, Vicente J Arán, Maria Luisa Jimeno, Enrique García-España, Julio Latorre, Maria J R Yunta
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 ((1)H and (13)C 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 CDCl(3) solution, 1 interacts with ethyleneurea (ETU), affording 1:1, 2:1, and 2:2 1-ETU complexes.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Dibutyltin(IV) oxide, 98%
Sigma-Aldrich
Diethanolamine, ACS reagent, ≥98.5%
Sigma-Aldrich
Dibutyltin(IV) oxide, purum
Sigma-Aldrich
Diethanolamine, puriss. p.a., ACS reagent, ≥99.0% (GC)
Supelco
Diethanolamine, analytical standard
Sigma-Aldrich
Diethanolamine, BioUltra, ≥99.5% (GC)
Supelco
Diethanolamine, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Diethanolamine, reagent grade, ≥98.0%
Sigma-Aldrich
Diethanolamine hydrochloride, 98%