7-bromo-4-methylsulfanylthieno[3,2-d]pyrimidine (270 mg, 1.0 mmol) was added to 1,4-dioxane (10 mL), and 4-methanesulfonyl-phenylboronic acid (310 mg, 1.6 mmol), tetrakis(triphenylphosphine)palladium(0) (71 mg, 0.062 mmol), and 2N aqueous sodium carbonate (3.1 mL, 3.1 mmol) were sequentially added thereto. The air present in the reaction mixture was removed using a nitrogen balloon, and the reaction mixture was heated to 100° C. and stirred for 4 hours. The reaction was terminated by addition of sodium bicarbonate, and the reaction mixture was extracted twice with ethyl acetate. The collected organic layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure to obtain a foamy residue. The residue was crystallized in the presence of diethyl ether to obtain the title compound (260 mg) as a yellowish solid.
