title: Regioselective synthesis of 1-alkyl- or 1-aryl-1H-indazoles via copper-catalyzed cyclizations of 2-haloarylcarbonylic compounds.
abstract: [reaction: see text] A general method for the one-step regioselective synthesis of 1-alkyl- or 1-aryl-1H-indazoles from ortho-halogenated alkanoylphenones, benzophenones, and arylcarboxylic acids, via copper-catalyzed amination, was developed by using 0.2% mol of CuO in the presence of K(2)CO(3). The reaction involves amination followed by intramolecular dehydration. Different functionalized alkyl aryl ketones, diaryl ketones, and benzoic acid derivatives were efficiently coupled with several hydrazines. Ligands commonly employed as catalysts for intermolecular amination were shown to be ineffective for this cyclization.
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, CIETUS, Campus Unamuno, 37007 Salamanca, Spain.
authors.forename: Dolores
authors.initials: D
authors.lastname: Viña
authors.forename: Esther
authors.initials: E
authors.lastname: del Olmo
authors.forename: José L
authors.initials: JL
authors.lastname: López-Pérez
authors.forename: Arturo
authors.initials: A
authors.lastname: San Feliciano
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D000478:Alkylation; D000586:Amination; D001555:Benzene Derivatives / Q000138:chemical synthesis; D001565:Benzoates / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D003500:Cyclization; D006834:Hydrazines / Q000737:chemistry; D006841:Hydrocarbons, Aromatic; D006846:Hydrocarbons, Halogenated / Q000737:chemistry*; D007191:Indazoles / Q000138:chemical synthesis*; D007659:Ketones / Q000737:chemistry*; D008024:Ligands; D008956:Models, Chemical; D011188:Potassium / Q000737:chemistry
chemical_list: D000447:Aldehydes; D001555:Benzene Derivatives; D001565:Benzoates; D002254:Carbonates; D002264:Carboxylic Acids; D006834:Hydrazines; D006841:Hydrocarbons, Aromatic; D006846:Hydrocarbons, Halogenated; D007191:Indazoles; D007659:Ketones; D008024:Ligands; D003300:Copper; C037593:potassium carbonate; D011188:Potassium; C000520:cuprous oxide