title: Selective base-promoted synthesis of substituted selenophenes by carbocyclization of (Z)-benzylselenoenynes.
abstract: We herein described the synthesis of several 3-benzyl-2,5-diarylselenophene derivatives in moderate to good yields using (Z)-benzylselenoenynes as starting material in carbocyclization reactions. The reactions were carried out under mild conditions using only t-BuOK as base, in the complete absence of transition metals or additives. The cyclized 3-benzyl-2,5-diarylselenophenes obtained in the current protocol appear highly promising and attractive intermediates for the synthesis of polysubstituted selenophenes. For instance, 3-benzyl-2,5-diphenylselenophene was treated with Br(2) provided the corresponding 3-benzyl-4-bromo-2,5-diphenylselenophene in high yield. 4-Bromoselenophene derivative was applied as substrate in the palladium catalyzed cross-coupling reactions with boronic acids to give the Suzuki type products in excellent yields.
authors.affiliation: Laboratório de Síntese, Reatividade, Avaliação Farmacológica e Toxicológica de Organocalcogênios, CCNE, UFSM, Santa Maria, Rio Grande do Sul, Brazil 97105-900.
authors.forename: Daniela A
authors.initials: DA
authors.lastname: Barancelli
authors.forename: Carmine I
authors.initials: CI
authors.lastname: Acker
authors.forename: Paulo H
authors.initials: PH
authors.lastname: Menezes
authors.forename: Gilson
authors.initials: G
authors.lastname: Zeni