504-29-0

27807-84-7

19741-30-1

The general procedure for the synthesis of 2-(imidazo[1,2-a]pyridin-2-yl)acetic acid from 2-aminopyridine (20 g, 212 mmol) and ethyl 4-chloro-3-oxobutanoate (28.7 mL, 212 mmol) is as follows: firstly, 2-aminopyridine was added to 300 mL of ethanol, followed by the addition to a reaction vessel containing a magnetic stir bar of 4-chloro-3- ethyl oxobutyrate. The reaction mixture was stirred at 80°C for 20 hours. Upon completion of the reaction, the ethanol was evaporated and the crude product was dissolved in 100 mL of 0.5 N hydrochloric acid. The aqueous phase was extracted three times with 50 mL of dichloromethane to remove organic impurities. The product was retained in the aqueous phase and 37 g of crude product was obtained by concentration under reduced pressure. The crude product was purified by silica gel chromatography using a dichloromethane/methanol gradient elution (yield: 8.3 g, 19% yield). The resulting ester was dissolved in 200 mL of methanol and 7 mL of 10 M sodium hydroxide solution was added. The reaction mixture was stirred at room temperature for 12 h until the ester was completely saponified. After evaporation of methanol, the aqueous phase was acidified to pH=7. The precipitated product was filtered and washed with ether (yield: 7.6 g, 99%).LCMS (Method 1): retention time (Rt) = 0.435 min; HRMS (ESIpos): m/z [M + H]+ C9H8N2O2 Calculated value 177.0659, measured value 177.0660.