2-Aminopyridine → 2-Methylimidazo(1,2-a)pyridine-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A mixture of pyridin-2-amine (10 g, 106 mmol), ethyl 2-chloro-3-oxobutanoate (16 g, 97 mmol) and ethanol (200 mL) was stirred at 80° C. for 2 days. The reaction mixture was concentrated under reduced pressure, saturated aqueous sodium bicarbonate solution was added to the obtained residue, and the mixture was extracted with ethyl acetate. The collected organic layer was washed with saturated brine and dried over anhydrous magnesium sulfate, and the insoluble material was filtered off. The filtrate was concentrated under reduced pressure, 8N aqueous sodium hydroxide solution (25 mL), water (75 mL) and ethanol (200 mL) were added to the obtained residue, and the mixture was stirred at 70° C. for 1 hr. 6N Hydrochloric acid (34 mL) was added dropwise to the reaction mixture under ice-cooling. The resulting precipitate was collected by filtration, washed with water, ethanol and diethyl ether and dried to give the title compound (7.6 g, 44%) as a pale-pink solid.

Provenance & Evidence