Microwave-assisted Ullmann-Buchwald C-S bond formation using a copper(I) catalyst and trans-cyclohexane-1,2-diol as ligand

Microwave irradiation of a thiophenol or alkyl thiol (1 equiv.) and an aryl halide (1 equiv.) in 2-propanol at 120 degrees C for three hours in the presence of K2CO3 (2 equiv.) as base using copper(I) iodide as catalyst (5 mol%) and trans-cyclohexane-1,2-diol (2 equiv.) as ligand provides a rapid and convenient method for C-S bond formation. The process is most efficient using thiophenol and aryl iodide precursors, both of which may contain electron-donating and electron-withdrawing groups, to give the corresponding diaryl sulfide in good to excellent yield.