A mixture of 6-bromo-1,2,2-trimethyl-2,3-dihydrothieno[3,2-d]pyrimidin-4(1H)-one (138 mg, 0.50 mmol), 3,5-dimethyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (333 mg, 1.50 mmol), sodium carbonate (265 mg, 2.50 mmol), 1,2-dimethoxyethane (5 mL) and water (2 mL) was purged with argon. Then, 1,1′-bis(diphenylphosphino)ferrocenepalladium (II) dichloride dichloromethane adduct (40.8 mg, 0.050 mmol) was added, and the mixture was purged with argon again. This mixture was refluxed for 18 h. Then, the mixture was poured into saturated aqueous NaHCO3 (100 mL) and EtOAc (100 mL), and the mixture was shaken well. The insoluble materials were filtered off. From the filtrate, the organic layer was collected, washed with brine, dried over MgSO4, filtered and concentrated under reduced pressure. This residue was purified by column chromatography (Purif, silica gel, 95:5 hexane/EtOAc to EtOAc, then EtOAc to 90:10 EtOAc/MeOH). The obtained yellow solid was triturated with EtOAc/hexane and collected by filtration to afford the title compound (52.2 mg, 36%) as a pale yellow solid:
