title: FeCl(3)-Diorganyl dichalcogenides promoted cyclization of 2-alkynylanisoles to 3-chalcogen benzo[b]furans.
abstract: A general synthesis of 3-chalcogen benzo[b]furans from the readily available 2-alkynylanisoles, via FeCl(3)/diorganyl dichalcogenides intramolecular cyclization, has been developed. Aryl and alkyl groups directly bonded to the chalcogen atom were used as cycling agents. The results revealed that the reaction significantly depends on the electronic effects of substituents in the aromatic ring bonded to the selenium atom of the diselenide species. We observed that the pathway of reaction was not sensitive to the nature of substituents in the aromatic ring of anisole since both the electron-donating and the electron-withdrawing groups delivered the products in similar yields. In addition, the obtained heterocycles were readily transformed to more complex products by using a chalcogen/lithium exchange reaction with n-BuLi followed by trapping of the lithium intermediate with aldehydes, furnishing the desired secondary alcohols in good yields.
authors: Laboratório de Síntese, Reatividade, Avaliação Farmacológica e Toxicológica de Organocalcogênios, CCNE, UFSM, Santa Maria-Rio Grande do Sul, Brazil 97105-900.
authors: Rafaela M
authors: RM
authors: Gay
authors: Flávia
authors: F
authors: Manarin
authors: Caroline C
authors: CC
authors: Schneider
authors: Daniela A
authors: DA
authors: Barancelli
authors: Michael D
authors: MD
authors: Costa
authors: Gilson
authors: G
authors: Zeni
mesh_terms: D000840:Anisoles / Q000737:chemistry*; D001572:Benzofurans / Q000138:chemical synthesis* / Q000737:chemistry; D018011:Chalcogens / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D003500:Cyclization; D005290:Ferric Compounds / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D000840:Anisoles; D001572:Benzofurans; D018011:Chalcogens; D002712:Chlorides; D005290:Ferric Compounds; C024555:ferric chloride