504-29-0

13176-46-0

101820-69-3

(1) To a 100 mL three-neck flask was added 10.83 g (51.8 mmol) of ethyl 4-bromo-3-oxobutanoate and 0.97 g of reaction promoter M (consisting of zinc nitrate and glycine in a weight ratio of 7:1, pre-dissolved in a solvent mixture of 10 mL of water and 20 mL of 1,4-dioxane). The reaction mixture was stirred at room temperature for 15 min, followed by the addition of 5.36 g (57 mmol) of 2-aminopyridine. The reaction system was warmed up to 70 °C with continuous stirring for 3.5 hours. The progress of the reaction was monitored by TLC until complete conversion of ethyl 4-bromo-3-oxobutanoate. After completion of the reaction, the mixture was filtered and the filtrate was concentrated under reduced pressure. It was extracted three times with 50 mL of water and washed three times with 50 mL of saturated brine. The organic phases were combined, the solvents were removed under reduced pressure and dried to give 10.17 g of a light yellow oily product, ethyl 2-(imidazo[1,2-a]pyridin-3-yl)acetate, in 94.1% yield and 97.9% purity.