title: Synthesis and structural characterization of 1- and 2-substituted indazoles: ester and carboxylic acid derivatives.
abstract: A series of indazoles substituted at the N-1 and N-2 positions with ester-containing side chains -(CH2)(n)CO2R of different lengths (n = 0-6, 9, 10) are described. Nucleophilic substitution reactions on halo esters (X(CH2)(n)CO2R) by 1H-indazole inalkaline solution lead to mixtures of N-1 and N-2 isomers, in which the N-1 isomer predominates. Basic hydrolysis of the ester derivatives allowed the synthesis of the corresponding indazole carboxylic acids. All compounds were fully characterised by multinuclear NMR and IR spectroscopies, MS spectrometry and elemental analysis; the NMR 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-ray diffraction, which shows a supramolecular architecture involving O2-H...N1 intermolecular hydrogen bonds.
authors.affiliation: INETI - Departamento de Tecnologia de Indústrias Químicas, Estrada do Paço do Lumiar, 22, 1649-038 Lisboa, Portugal. fatima.teixeira@ineti.pt
authors.forename: Fátima C
authors.initials: FC
authors.lastname: Teixeira
authors.forename: Hélène
authors.initials: H
authors.lastname: Ramos
authors.forename: Inês F
authors.initials: IF
authors.lastname: Antunes
authors.forename: M João M
authors.initials: MJ
authors.lastname: Curto
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Duarte
authors.forename: Isabel
authors.initials: I
authors.lastname: Bento
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D002247:Carbon Isotopes; D002264:Carboxylic Acids / Q000138:chemical synthesis* / Q000737:chemistry*; D004952:Esters / Q000138:chemical synthesis* / Q000737:chemistry*; D006860:Hydrogen Bonding; D007191:Indazoles / Q000138:chemical synthesis* / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D013237:Stereoisomerism
chemical_list: D002247:Carbon Isotopes; D002264:Carboxylic Acids; D004952:Esters; D007191:Indazoles; D019342:Acetic Acid