We examined the coupling of 4-iodotoluene and phenyl acetylene in the presence of 0.001 mol% of Pd(acac) 2 in DMSO with K 3 PO 4 as a base under an argon atmosphere at 125 ˚C for 24 hours. In the presence of 10 mol% of CuI and ligand 1a, 1-methyl-4-(phenylethynyl)benzene (3a) was obtained in good yield (entry 1, Table [¹] ). The reaction gave low yield of the desired product in the absence of CuI (Table [¹] , entry 2). Without Pd(acac) 2 and CuI, the reaction ...