Acetic Acid → Ethyl 4-Ethoxy-2-oxo-1,2-dihydropyridine-3-carboxylate

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Reaction Conditions

Reaction Steps

(4E)-Ethyl 2-cyano-5-(dimethylamino)-3-ethoxypenta-2,4-dienoate (20 kg) and acetic acid (126 L) were charged to a reactor and heated to 100° C. for 3 hrs until the reaction was complete as characterized by HPLC. The reaction mass was cooled to 55° C. and acetic acid was removed by vacuum distillation at 65-75° C. After distillation, the mixture was cooled to room temperature and water (3 L) was added. The pH of the mixture was adjusted to 8 by addition of 100 L of a 30% sodium carbonate solution. The solids were filtered off and washed with 10 L of water. The combined aqueous layers were extracted three times with DCM (100 L). The combined DCM layers were washed with brine, then dried over sodium sulfate and concentrated to dryness. Ethyl acetate was added to the concentrate. The mixture was heated to 40° C. and then cooled to 25° C. The solids were filtered off, washed with petroleum ether and dried at room temperature for 12 hrs to yield ethyl 4-ethoxy-2-oxo-1,2-dihydropyridine-3-carboxylate (10.3 kg; 58.5% yield).

Provenance & Evidence