Synthesis of 2,3-Bis(arylamino)benzofurans and 2,3-Bis(aryIimino)-2,3-dihy-drobenzofurans by a Lewis Acid Catalyzed Reaction of 2-Aryliminophenols with Aryl Isocyanides

摘要

An efficient method for the preparation of 2,3-bis(aryl-amino)benzofurans and 2,3-bis(arylimino)-2,3-dihydrobenzofurans is described that is based on the reaction of 2-aiyliminophenols with aiyl isocyanides in the presence of a catalytic amount of boron tri-fluoride diethyl etherate. The reaction gives 2,3-bis(arylamino)ben-zofurans, some of which are transformed into 2,3-bis(arylimino)-2,3-dihydrobenzofurans by air oxidation, mostly during workup.Because some molecules containing a benzofiiran moiety are known to display a variety of biological activities,1 the development of new, efficient methods for the synthesis of benzofurans continues to be of interest.2 In this paper we report a facile preparation of 2,3-diaminobenzofuran derivatives, 2,3-bis(aiylimino)-2,3-dihydrobenzofurans and 2,3-bis(arylamino)benzofurans, by a Lewis acid catalyzed reaction of readily available 2-aryliminophenols with aryl isocyanides. There have been only a few reports on the synthesis of these types of benzofuran derivatives.