Ethanol → (S)-2-(4-Chlorophenyl)-alpha-methyl-3H-imidazo[4,5-b]pyridine-3-acetic acid ethyl ester

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Reaction Steps

A suspension of crude (S)-2-(4-chlorophenyl)-α-methyl-3H-imidazo[4,5-b]pyridine-3-acetic acid (2.0 g, 0.00663 mole) in absolute ethanol was stirred at room temperature while 4 drops of concentrated sulfuric acid was added. The reaction mixture was refluxed for three days. Approximately 1/2 to 2/3 of the solvent was removed under reduced pressure. Saturated sodium bicarbonate solution (20 ml) was added to the remaining solution. The product was extracted into two portions of ethyl acetate and the combined organic layers were washed twice with water, dried over sodium sulfate, filtered and evaporated to an oil which was dissolved in hot absolute ethanol. Water was added to the cloud point and upon cooling to room temperature, a solid precipitated. The solid was collected by filtration, rinsed with water and dried under high vacuum at 50° C. to give 1.48 g (68%) of title compound, mp 103°-106° C.

Provenance & Evidence