Cesium carbonate → 1,2,2-trimethyl-6-(5-methyl-1H-pyrazol-4-yl)-2,3-dihydrothieno[3,2-d]pyrimidin-4(1H)-one

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Reaction Steps

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-methyl-4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-1H-pyrazole (208 mg, 1.00 mmol), cesium carbonate (489 mg, 1.50 mmol), 1,2-dimethoxyethane (5 mL) and water (1 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. After cooling to room temperature, 3-methyl-4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-1H-pyrazole (0.208 g, 1.00 mmol), Cs2CO3 (0.489 g, 1.50 mmol), 1,2-dimethoxyethane (5 mL) and water (1 mL) were added. The mixture was purged with argon. Then, 1,1′-bis(diphenylphosphino)ferrocenepalladium (II) dichloride dichloromethane adduct (0.041 g, 0.050 mmol) was added, and the mixture was purged with argon again. The mixture was refluxed for 6 h. Then, the mixture was poured into saturated aqueous NaHCO3 (100 mL) and extracted with EtOAc (100 mL), and the extract was 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). The obtained yellow solid was triturated with EtOAc and collected by filtration to afford the title compound (52.7 mg, 38%) as a pale yellow solid:

Provenance & Evidence