title: Synthesis of pyridazinones through the copper(I)-catalyzed multicomponent reaction of aldehydes, hydrazines, and alkynylesters.
abstract: The copper-catalyzed multicomponent cyclization reaction, which combined aldehydes, hydrazines, and alkynylesters, was applied in the synthesis of pyridazinones. The reaction was regioselective and gave only six-membered pyridazinones in the complete absence of five-membered pyrazoles or a regioisomeric mixture. During this investigation, the use of 2-halobenzaldehyde as the starting material, under identical reaction conditions, gave 6-(2-ethoxyphenyl)pyridazinones after sequential Michael addition/1,2-addition/Ullmann cross-coupling reactions.
authors.affiliation: Departamento de Química Orgânica Laboratório de Síntese, Reatividade, Avaliação Farmacológica e Toxicológica de Organocalcogênios, Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul, 97105-900 (Brazil).
authors.forename: Anderson C
authors.initials: AC
authors.lastname: Mantovani
authors.forename: Tales A C
authors.initials: TA
authors.lastname: Goulart
authors.forename: Davi F
authors.initials: DF
authors.lastname: Back
authors.forename: Gilson
authors.initials: G
authors.lastname: Zeni
mesh_terms: D000447:Aldehydes / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D003500:Cyclization; D006834:Hydrazines / Q000737:chemistry; D008958:Models, Molecular; D011724:Pyridazines / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000447:Aldehydes; D006834:Hydrazines; D011724:Pyridazines; D003300:Copper
keywords: copper; cyclization; heterocycles; homogeneous catalysis; multicomponent reactions