Sal de Bunte como precursor para a síntese de 3- organotio-benzo[b]furanos

Abstract

In this work we developed a methodology for the synthesis of 3-orgnanylthio-benzo[b]furan derivatives, aiming to elaborate a satisfactory procedure. This method is based on the application of an alternative source of organosulfur in intramolecular cyclization reactions of o-alkynylanisoles from Bunte salts, catalyzed by copper salts. In order to optimize the reaction conditions, a series of copper salts were investigated, with emphasis on copper(II) bromide, which showed the best efficiency. The reactions were carried out under mild conditions, with the use of a low-cost copper catalyst and without the presence of thiols, disulfides and sulfenyl halides, which from an economic and operational point of view is advantageous. Initially, the reactions were conducted using 1-methoxy-2-(phenylethynyl)-benzene and benzyl Bunte salt, showing to be efficient. The optimized reaction condition provided the isolation of the compound 3-(benzylthio)-2-phenyl-benzo[b]furan 3 in 40% yield. The obtained compound was structurally characterized by GC-MS and 1H, 13C NMR techniques.