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Molecules 2006, 11(11), 867-889; doi:10.3390/11110867
Article

Synthesis and Structural Characterization of 1- and 2-Substituted Indazoles: Ester and Carboxylic Acid Derivatives

1,* , 1, 1, 1, 2 and 3
1 INETI - Departamento de Tecnologia de Indústrias Químicas, Estrada do Paço do Lumiar, 22, 1649-038 Lisboa, Portugal 2 Instituto Superior Técnico, Centro de Química Estrutural, Complexo I, Av. Rovisco Pais, 1049-001 Lisboa, Portugal 3 Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127, 2781-901 Oeiras, Portugal
* Author to whom correspondence should be addressed.
Received: 4 October 2006 / Revised: 30 October 2006 / Accepted: 13 November 2006 / Published: 14 November 2006
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Abstract

A series of indazoles substituted at the N-1 and N-2 positions with ester-containing side chains -(CH2)nCO2R of different lengths (n = 0-6, 9, 10) are described.Nucleophilic substitution reactions on halo esters (X(CH2)nCO2R) by 1H-indazole inalkaline solution lead to mixtures of N-1 and N-2 isomers, in which the N-1 isomerpredominates. Basic hydrolysis of the ester derivatives allowed the synthesis of thecorresponding indazole carboxylic acids. All compounds were fully characterised bymultinuclear NMR and IR spectroscopies, MS spectrometry and elemental analysis; theNMR spectroscopic data were used for structural assignment of the N-1 and N-2 isomers.The molecular structure of indazol-2-yl-acetic acid (5b) was determined by X-raydiffraction, which shows a supramolecular architecture involving O2-H...N1intermolecular hydrogen bonds.
Keywords: Indazole; N-1 and N-2 isomers; Spectroscopic characterization; X-ray diffraction studies. Indazole; N-1 and N-2 isomers; Spectroscopic characterization; X-ray diffraction studies.
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Teixeira, F.C.; Ramos, H.; Antunes, I.F.; Curto, M.J.M.; Duarte, M.T.; Bento, I. Synthesis and Structural Characterization of 1- and 2-Substituted Indazoles: Ester and Carboxylic Acid Derivatives. Molecules 2006, 11, 867-889.

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