Potassium Carbonate → Ethyl 5-bromopyrazolo[1,5-a]pyridine-3-carboxylate

Participants

Reaction Steps

Into a 250-mL three neck round-bottom flask, was placed a solution of 1-amino-4-bromopyridin-1-ium iodide (compound 64.2, 15 g, ˜50% purity, 24.9 mmol) in N,N-dimethylformamide (80 mL). Potassium carbonate (10.6 g, 76.7 mmol) was added portion-wise followed by the addition of ethyl propiolate (11.7 mL, 115 mmol) drop-wise over 10 min. The resulting mixture was stirred overnight at room temperature, then diluted with EtOAc (300 mL) and water (100 mL). The solids were removed by filtration and the organic layer was washed with brine (3×50 mL), dried (Na2SO4), filtered, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography with ethyl acetate/petroleum ether (1:10) as the eluent to yield the title compound as a brown solid (300 mg, 6%).

Provenance & Evidence