A 100-mL single-neck round-bottomed flask equipped with a magnetic stirrer and a reflux condenser was charged with pyrazin-2-amine (500 mg, 5.3 mmol), 3,5-dibromo-1-methyl pyridin-2(1H)-one (1335 mg, 5.3 mmol), Pd2(dba)3 (229 mg, 0.25 mmol), XantPhos (289 mg, 0.50 mmol), cesium carbonate (3.26 g, 10 mmol) and 1,4-dioxane (50 mL). After three cycles of vacuum/argon flush, the mixture was stirred at 100° C. for 2 h. It was then filtered and the filtrate was evaporated in vacuo. The residue was purified by silica-gel column chromatography eluting with 50:1 dichloromethane/methanol to afford 162a (420 mg, 30%) as a yellow solid. MS-ESI: [M+H]+ 281.0.
