Triethylamine → 6-Methyl-2-(4-methylphenyl)-alpha-oxo-imidazo[1,2-a]pyridine-3-acetic Acid Ethyl Ester

関与物質

反応条件

反応手順

A suspension of potassium monoethyl oxalate (84.3 g; 0.54 mols) in methylene chloride (395 mL) is added dropwise with phosphorous oxychloride (82.8 g; 0.54 mols) keeping the temperature at about 30° C. After 4÷6 hours, 2-(4-methylphenyl)-6-methylimidazo[1,2-a]-pyridine (100.0 g; 0.45 mols) is added, keeping the temperature below 35° C. The resulting suspension is added dropwise with triethylamine (50.5 g; 0.50 mols) keeping the mixture at the reflux temperature. After one hour under these conditions, the reaction mixture is cooled to 5÷10° C. and poured into a suspension of sodium carbonate (95 g; 0.89 mols) in water (500 mL) keeping the temperature below 35° C. The phases are separated and the upper aqueous phase is reextracted with methylene chloride (45 mL). The combined organic phases are washed with water (45 mL) and concentrated to a residue under vacuum. The solid residue is taken up in ethanol (590 mL), heated to dissolution and left to crystallize. After cooling to about 0° C. the solid is filtered, washed with ethanol and dried at 50° C. under vacuum to obtain ethyl 2-(4-methylphenyl)-6-methylimidazo[1,2-a]-pyridine-3-glyoxalate (141.5 g, 99.5% titre, 97.5% yield).

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