Synthesis of Thieno[3,2-b]benzofurans by Palladium-catalyzed Intramolecular C-H/C-H Coupling

The intramolecular C-H/C-H coupling of 3-aryloxythiophenes and 3-aryloxybenzo[b]thiophenes has been found to occur effectively in the presence of Pd(TFA)(2) and AgOAc as catalyst and oxidant, respectively, to afford the corresponding cyclized products, thieno[3,2-b]benzofurans and [1]benzothieno [3,2-b]benzofurans.