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 1 00 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