Cesium carbonate → Tert-butyl 4-(6-((5-bromo-1-methyl-2-oxo-1,2-dihydropyridin-3-yl)amino)pyridin-3-yl)piperazine-1-carboxylate

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Reaction Steps

A 100-mL single-neck round-bottomed flask equipped with a magnetic stirrer and a reflux condenser was charged with 339b (1.3 g, 4.7 mmol), 3,5-dibromo-1-methylpyridin-2(1H)-one (1.24 g, 4.7 mmol), cesium carbonate (3.8 g, 12 mmol), and 1,4-dioxane (50 mL). After bubbling nitrogen through the resulting mixture for 30 minutes, XantPhos (272 mg, 0.47 mmol) and tris(dibenzylideneacetone)dipalladium(0) (430 mg, 0.47 mmol) were added. The system was subjected to three cycles of argon/vacuum flush and heated at reflux for 3 h. After this time the reaction was cooled to room temperature and filtered. The filtrate was partitioned between ethyl acetate (100 mL) and water (100 mL). The aqueous layer was separated and extracted with ethyl acetate (2×50 mL). The combined organic layer was washed with brine (50 mL) and dried over sodium sulfate. The drying agent was removed by filtration and the filtrate was concentrated under reduced pressure. The residue was purified by silica-gel column chromatography eluting with 50:1 dichloromethane/methanol to afford 339c (1.3 g, 59%). MS-ESI: [M+H]+ 464.

Provenance & Evidence