A 100-mL single-neck round-bottomed flask equipped with a magnetic stirrer and a reflux condenser was charged with 1,4-dioxane (20 mL), 154a (500 mg, 5.10 mmol), 3,5-dibromo-1-methylpyridin-2(1H)-one (1362 mg, 5.10 mmol), and cesium carbonate (3.325 g, 10.2 mmol). After bubbling nitrogen through the suspension for 20 minutes, Xantphos (0.59 g, 1.02 mmol) and tris(dibenzylideneacetone)dipalladium(0) (467 mg, 0.51 mmol) were added. The system was subjected to three cycles of vacuum/nitrogen flush and heated at reflux for 5 h. It was then cooled to room temperature and filtered. The filtrate was evaporated under reduced pressure. The residue was purified by silica-gel column chromatography eluting with 50:1 dichloromethane/methanol to afford 154b (220 mg, 15%) as a brown solid. LCMS: [M+H]+ 284.1
