Synthesis and structural characterization of 1- and 2-substituted indazoles: ester and carboxylic acid derivatives.
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.
Teixeira
Fátima C
FC
INETI - Departamento de Tecnologia de Indústrias Químicas, Estrada do Paço do Lumiar, 22, 1649-038 Lisboa, Portugal. fatima.teixeira@ineti.pt
Ramos
Hélène
H
Antunes
Inês F
IF
Curto
M João M
MJ
Duarte
M Teresa
MT
Bento
Isabel
I
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
D002247:Carbon Isotopes; D002264:Carboxylic Acids; D004952:Esters; D007191:Indazoles; D019342:Acetic Acid