title: Cyclization of homopropargyl chalcogenides by copper(II) salts: selective synthesis of 2,3-dihydroselenophenes, 3-arylselenophenes, and 3-haloselenophenes/thiophenes.
abstract: Copper(II) halide mediated cyclization of homopropargyl chalcogenides gave three types of chalcogenophene derivatives. Selective product formation was achieved by controlling solvent, temperature, and atmosphere. By using CuBr2 and 1,2-dichloroethane at room temperature under ambient atmosphere, 4-bromo dihydroselenophene derivatives were obtained, whereas CuBr2 and 1,2-dichloroethane at reflux gave selectively 2-substituted selenophenes. When 1,2-dichloroethane was replaced by dimethylacetamide, 3-halo-selenophenes were obtained exclusively. The versatility of chalcogenophenes was also studied by reaction of 3-haloselenophenes with terminal alkynes under Sonogashira conditions affording the cross-coupled products. In addition, the reaction of 3-haloselenophenes with boronic acids gave the corresponding Suzuki-type products in good yields.
authors.affiliation: 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: Ricardo F
authors.initials: RF
authors.lastname: Schumacher
authors.forename: Alisson R
authors.initials: AR
authors.lastname: Rosário
authors.forename: Marlon R
authors.initials: MR
authors.lastname: Leite
authors.forename: Gilson
authors.initials: G
authors.lastname: Zeni
mesh_terms: D001897:Boronic Acids / Q000737:chemistry; D018011:Chalcogens / Q000138:chemical synthesis* / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D003500:Cyclization; D005025:Ethylene Dichlorides / Q000737:chemistry; D006846:Hydrocarbons, Halogenated / Q000138:chemical synthesis* / Q000737:chemistry; D016566:Organoselenium Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010293:Pargyline / Q000138:chemical synthesis* / Q000737:chemistry; D012492:Salts; D013876:Thiophenes / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: C558238:2,3-dihydroselenophene; D001897:Boronic Acids; D018011:Chalcogens; D005025:Ethylene Dichlorides; D006846:Hydrocarbons, Halogenated; D016566:Organoselenium Compounds; D012492:Salts; D013876:Thiophenes; C024565:ethylene dichloride; D003300:Copper; D010293:Pargyline
keywords: copper; cyclization; heterocycles; selenium heterocycles; synthetic methods