To a solution of methyl 4-bromo-3-methyl-2-thiophenecarboxylate (300 mg, 1.27 mmol) in dioxane/H2O (5 mL/1 mL) was added K2CO3 (525 mg, 3.80 mmol), tetrakistriphenylphosphine Pd(0) (15 mg, 0.01 mmol), and 1-methyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (345 mg, 1.7 mmol). The reaction mixture was heated to 70° C. in a sealed tube for 2 h. The reaction solution was concentrated under vacuum and purified on silica gel (hexanes/EtOAc, 9:1 to 4:1) to give the title compound (270 mg, 90%): LC-MS (ES) m/z 237 (M+H)+.
