Cesium carbonate → 2-(5-Bromo-1-methyl-2-oxo-1,2-dihydropyridin-3-ylamino)-5-methyl-4,5-dihydropyrazolo[1,5-a]pyrazin-6(7H)-one

Participants

Reaction Steps

A 100-mL round-bottomed flask equipped with a magnetic stirrer and a reflux condenser was charged with 146d (300 mg, 1.8 mmol), 3,5-dibromo-1-methylpyridin-2(1H)-one (482 mg, 1.8 mmol), cesium carbonate (1.17 g, 3.6 mmol), and 1,4-dioxane (20 mL). After bubbling nitrogen through the suspension for 10 minutes, xantphos (104 mg, 0.18 mmol) and tris(dibenzylideneacetone)dipalladium(0) (82 mg, 0.090 mmol) were added. The system was subjected to three cycles of vacuum/argon flush and heated at reflux for 5 h. It was then cooled to room temperature and filtered. The solid was washed with dichloromethane (2×30 mL). The combined filtrate was concentrated under reduced pressure. The residue was purified by silica-gel column chromatography eluting with dichloromethane/methanol (80/1 to 30/1) to afford 146e (390 mg, 61%) as a yellow solid.

Provenance & Evidence