Acetic Anhydride → 1-(Imidazo[1,2-a]pyridin-3-yl)ethan-1-one

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Reaction Steps

25 g of imidazo[1,2-a]pyridine was dissolved in 350 mL of chloroform, and 56.4 g of aluminum chloride was added under an ice-cold condition over 30 minutes. The mixture was stirred overnight at room temperature, and then heated up to the temperature of 50° C. 16 mL of acetic anhydride was added and the mixture was stirred at 50° C. for 90 minutes. After cooling the reaction solution back to room temperature, ice water was added, and a 3N aqueous solution of sodium hydroxide was further added until the mixture becomes basic. The insolubles were separated by filtration through celite, the filtrate was extracted with ethyl acetate, and the organic layer was washed with saturated brine. The layer was dried over anhydrous sodium sulfate and then filtered, and the filtrate was concentrated to obtain 1-imidazo[1,2-a]pyridine-3-ylethanone [1-1] as a brown oily product. The obtained Compound [1-1] was used in the subsequent reaction without further purification.

Provenance & Evidence