A 100-mL single-neck round-bottomed flask equipped with a magnetic stirrer and a reflux condenser was charged with 337c (400 mg, 3.60 mmol), 3,5-dibromo-1-methylpyridin-2(1H)-one (960 mg, 3.60 mmol), XantPhos (240 mg, 0.40 mmol), tris(dibenzylideneacetone)dipalladium(0) (360 mg, 0.40 mmol), Cs2CO3 (4.69 g, 14.4 mmol), and 1,4-dioxane (20 mL). After three cycles of vacuum/nitrogen flush, the mixture was heated at 90° C. for 2.5 h. It was then cooled to room temperature and filtered. The filtrate was concentrated under reduced pressure and the resulting residue was purified by silica-gel column chromatography eluting with dichloromethane/methanol (30:1 to 20:1) to afford 337d as a pale yellow solid (350 mg, 33%). MS-ESI: [M+H]+ 297.1.
