title: FeCl3-diorganyl dichalcogenides promoted cyclization of 2-organochalcogen-3-alkynylthiophenes: synthesis of chalcogenophene[2,3-b]thiophenes.
abstract: We report here our results on the FeCl3-diorganyl dichalcogenides intramolecular cyclization of 2-organochalcogen-3-alkynylthiophenes. The cyclization reaction proceeded cleanly under mild reaction conditions giving the (S)-Se-, (S)-S- and (S)-Te-heterocycles in good yields. In addition, the obtained chalcogenophenes were readily transformed into more complex products using the palladium cross-coupling reaction with boronic acids. Conversely, using a metal-halogen exchange reaction with n-BuLi, the chalcogenophenes produced the lithium-intermediate which was trapped with aldehyde furnishing the desired secondary alcohol in good yield.
authors.affiliation: Laboratório de Síntese, Reatividade, Avaliação Farmacológica e Toxicológica de Organocalcogênios, CCNE, UFSM, Santa Maria - Rio Grande do Sul, 97105-900, Brazil.
authors.forename: André L
authors.initials: AL
authors.lastname: Stein
authors.forename: Filipe N
authors.initials: FN
authors.lastname: Bilheri
authors.forename: Alisson R
authors.initials: AR
authors.lastname: Rosário
authors.forename: Gilson
authors.initials: G
authors.lastname: Zeni
mesh_terms: D002384:Catalysis; D018011:Chalcogens / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D003500:Cyclization; D005290:Ferric Compounds / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D018011:Chalcogens; D002712:Chlorides; D005290:Ferric Compounds; D013876:Thiophenes; D010165:Palladium; D008094:Lithium; C024555:ferric chloride