Water → 4-fluorophenyl-3H-imidazo[4,5-b]pyridine-3-acetic acid

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Reaction Steps

A solution of N-[3-[(4-fluorobenzoyl)amino]-2-pyridinyl]glycine ethyl ester (70.0 g, 0.2205 mole) in ethylene glycol was refluxed for 2 hours, cooled and 14% of the solution was removed. To the remaining solution (0.19 mole) was added 88 ml of water and solid potassium hydroxide pellets (21.4 g, 0.38 mole). The solution was heated at reflux for an additional 11/4 hours, filtered into ice water (2 liter) and acidified with 3N hydrochloric acid. The resulting solid was collected by filtration, washed with water and dried under high vacuum at 60° C. overnight to give 45.5 g of crude title compound (88% yield). A 3.5-g porton of the solid was dissolved in hot methanol and filtered while hot, and water was added to the cloud point. Upon cooling to room temperature, solid precipitated which was collected and recrystallized again from methanol/water to give 2.00 g of title compound after drying under high vacuum at 50° C., mp >250° C.

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