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Synthesis and Structural Characterization of 1- and 2-Substituted Indazoles: Ester and Carboxylic Acid Derivatives
INETI - Departamento de Tecnologia de Indústrias Químicas, Estrada do Paço do Lumiar, 22, 1649-038 Lisboa, Portugal
Instituto Superior Técnico, Centro de Química Estrutural, Complexo I, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
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; in revised form: 30 October 2006 / Accepted: 13 November 2006 / Published: 14 November 2006
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.
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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.
Teixeira FC, Ramos H, Antunes IF, Curto MJM, Duarte MT, Bento I. Synthesis and Structural Characterization of 1- and 2-Substituted Indazoles: Ester and Carboxylic Acid Derivatives. Molecules. 2006; 11(11):867-889.
Teixeira, Fátima C.; Ramos, Hélène; Antunes, Inês F.; Curto, M. J.M.; Duarte, M. T.; Bento, Isabel. 2006. "Synthesis and Structural Characterization of 1- and 2-Substituted Indazoles: Ester and Carboxylic Acid Derivatives." Molecules 11, no. 11: 867-889.