1-Hydroxybenzotriazole → 6-[4-(5-methylimidazo[1,2-a]pyridine-2-carbonyl)-1-piperazinyl]-3,4-dihydro-2(1H)-quinolinone

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Reaction Steps

A mixture of 5-methylimidazo[1,2-a]pyridine-2-carboxylic acid (704 mg), 1-hydroxybenzotriazole (648 mg), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (917 mg) and N,N-dimethylformamide (25 ml) was stirred for 1 hour at ambient temperature. 1-(1-piperazinyl)-3,4-dihydro-2(1H)-quinolinone (924 mg) was added thereto, and the mixture was stirred for 10 hours at the same temperature. After the solvent was removed, to the residue were added 5% solution of methanol in chloroform (30 ml) and water (20 ml), and the mixture was adjusted to pH 9 with a saturated aqueous solution of potassium carbonate. The separated organic layer was dried over magnesium sulfate and concentrated. The residue was subjected to a column chromatography on silica gel (80 g) and eluted with 10% solution of methanol in chloroform. The fractions containing the desired compound were collected and concentrated. The residual crystal was recrystallized from methanol-ethyl acetate to give 6-[4-(5-methylimidazo[1,2-a]pyridine-2-carbonyl)-1-piperazinyl]-3,4-dihydro-2(1H)-quinolinone (0.8 g).

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