Triethylamine → diethyl 3-(p-chlorophenyl)-4-methyl-2-oxo-2H-pyrano[2,3-b]pyridine-6,7-dicarboxylate

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Reaction Steps

Diethyl 5-acetyl-1,6-dihydro-6-oxo-2,3-pyridinedicarboxylate, (6.0 g, 0.0213 mol), 4-chlorophenyl acetic acid (3.64 g, 0.0213 mol) and triethylamine (3.0 g, 1.5 eq) are refluxed in 50 mL of acetic anhydride for three and one-half hours and then stirred at room temperature overnight. The reaction mixture is poured into 100 mL of ice cold water and the pH is adjusted to 8 with an ammonium hydroxide solution. The crystalline solid is filtered, washed with water, dried and dissolved in 100 mL of methylene chloride. The solution is dried over anhydrous sodium sulfate and the solvent removed under reduced pressure to give the desired product (8.8 g, 99%), which is crystallized from ethyl acetate to give the pure product having a melting point 179°-181° C.

Provenance & Evidence