Studies On The Cross-Coupling Reaction Between2-Alkylthio Benzofurans And Ary Boronic Acids

2-Aryl benzofuran derivatives are important heterocyclic compounds bearingstrong biological and pharmacological activities and widely applied in clinical drugs.Therefore, investigations of simple and general methods to synthesize2-arylbenzofurans have been paid much attention.Liebeskind-Srogl reaction provides an important entry to ketone compounds byPd-catalyzed desulfitative C–C bond-forming reaction between thioester andorganoboronic acids under the neutral condition. Over the passed ten years,Liebeskind-Srogl reaction has earned a place in the list of this rapidly growing field.And the thioorganic coupling partners have been gradually extended from thioestersto heteroaromatic thioethers, alkynyl thioethers, cyclic thioamides, isothiourea and soon. Recently, an aerobic, Cu-catalyzed desulfitative C–C bond-forming reaction ofketene dithioacetals/vinylogous thioesters and arylboronic acids has been developedin our group.Aiming to develop a newly efficient method for the synthesis of2-arylbenzofurans, the desulfitative C–C cross coupling reaction between2-alkylthiobenzofurans and organoboronic acids was investigated in this work. Thus,2-arylbenzofurans were successfully achieved in high yields. By this reaction, coumestans,which were isolated from plant extracts and showed interesting pharmacologicalactivities, were also prepared by using2-hydroxyl arylboronic acids as the couplingpartners.