title: Efficient MW-Assisted Synthesis, Spectroscopic Characterization, X-ray and Antioxidant Properties of Indazole Derivatives.
abstract: A small series of tetrahydroindazoles was prepared, starting from 2-acetylcyclohexanone and different hydrazines using reflux and a focused microwave reactor. Microwave irradiation (MW) favored the formation of the desired products with improved yields and shortened reaction times. This is a simple and green method for the synthesis of substituted tetrahydroindazole derivatives. The in vitro antioxidant activity was evaluated using the DPPH and ABTS methods. In these assays, 2-(4-fluorophenyl)-3-methyl-4,5,6,7-tetrahydro-2H-indazole (3f) showed moderate DPPH decoloring activity, while 3-methyl-4,5,6,7-tetrahydro-1H-indazole (3a), 3-methyl-2-phenyl-4,5,6,7-tetrahydro-2H-indazole (3b) and 2-(4-fluorophenyl)-3-methyl-4,5,6,7-tetrahydro-2H-indazole (3f) were the most active in the ABTS assay. All compounds were well characterized by IR, ¹H-, (13)C-NMR and GC-MS spectroscopy and physical data, while the structure of 4-(3-methyl-4,5,6,7-tetrahydro-2H-indazol-2-yl)benzoic acid (3e) was also determined by single crystal X-ray analysis.
authors.affiliation: Organic Synthesis Laboratory and Biological Activity (LSO-Act-Bio), Institute of Chemistry of Natural Resources, Universidad de Talca, Casilla 747, Talca 3460000, Chile. epolo@utalca.cl.
authors.forename: Efrain
authors.initials: E
authors.lastname: Polo
authors.affiliation: Grupo/Semillero de Investigaci&#243;n en Compuestos Heteroc&#237;clicos, Programa de Qu&#237;mica, Facultad de Ciencias B&#225;sicas, Universidad del Atl&#225;ntico, Km 7 Antigua v&#237;a Puerto Colombia, Barranquilla 081007, Atl&#225;ntico, Colombia. jorgetrilleras@mail.uniatlantico.edu.co.
authors.forename: Jorge
authors.initials: J
authors.lastname: Trilleras
authors.affiliation: Grupo/Semillero de Investigaci&#243;n en Compuestos Heteroc&#237;clicos, Programa de Qu&#237;mica, Facultad de Ciencias B&#225;sicas, Universidad del Atl&#225;ntico, Km 7 Antigua v&#237;a Puerto Colombia, Barranquilla 081007, Atl&#225;ntico, Colombia. jotaramos87@gmail.com.
authors.forename: Juan
authors.initials: J
authors.lastname: Ramos
authors.affiliation: Solid State Chemistry Laboratory, Science Faculty, University of Chile, Santiago, 7800003, Chile. agaldamez@uchile.cl.
authors.forename: Antonio
authors.initials: A
authors.lastname: Galdámez
authors.affiliation: Heterocyclic Compounds Research Group, Department of Chemistry, Universidad del Valle, Cali A.A. 25360, Colombia. jairo.quiroga@correounivalle.edu.co.
authors.forename: Jairo
authors.initials: J
authors.lastname: Quiroga
authors.affiliation: Organic Synthesis Laboratory and Biological Activity (LSO-Act-Bio), Institute of Chemistry of Natural Resources, Universidad de Talca, Casilla 747, Talca 3460000, Chile. mgutierrez@utalca.cl.
authors.forename: Margarita
authors.initials: M
authors.lastname: Gutierrez
mesh_terms: D000975:Antioxidants / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D060326:Chemistry Techniques, Synthetic; D055772:Green Chemistry Technology; D006860:Hydrogen Bonding; D007191:Indazoles / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D008872:Microwaves; D008958:Models, Molecular; D015394:Molecular Structure; D013057:Spectrum Analysis; D013696:Temperature
chemical_list: D000975:Antioxidants; D007191:Indazoles
keywords: antioxidant activity; green chemistry; microwave irradiation; tetrahydroindazole