A 250-mL single-neck round-bottomed flask equipped with a magnetic stirrer and a reflux condenser was charged with pyrazin-2-amine (1.0 g, 10 mmol), 3,5-dibromo-1-methylpyridin-2(1H)-one (2.7 g, 10 mmol), Pd2(dba)3 (460 mg, 0.50 mmol), XantPhos (600 mg, 1.0 mmol), cesium carbonate (6.52 g, 20 mmol), and 1,4-dioxane (150 mL). After three cycles of vacuum/argon flash, the mixture was heated at 100° C. for 2 h. It was then filtered and the filtrate was evaporated in vacuo. The residue was purified by recrystallization with methanol to afford 160a (1.3 g, 47%) as a light green solid. MS-ESI: [M+H]+ 281.0.
