1174046-84-4

General procedure for the synthesis of ethyl 2-oxo-4-ethoxy-1,2-dihydropyridine-3-carboxylate from ethyl 2-cyano-5-(dimethylamino)-3-ethoxypenta-2,4-dienoate: ethyl 2-cyano-5-(dimethylamino)-3-ethoxypenta-2,4-dienoate (15.0 g, 63 mmol) was mixed with acetic acid (600 mL) and reacted at reflux overnight. After completion of the reaction, the mixture was cooled to room temperature and concentrated under reduced pressure to remove the solvent. The residue was treated with water and washed with ethyl acetate (2×). The aqueous layer was adjusted to pH 9-10 with sodium bicarbonate and extracted with dichloromethane (3×). The organic layers were combined, washed with saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure. Finally, it was purified by silica gel column chromatography to afford ethyl 2-oxo-4-ethoxy-1,2-dihydropyridine-3-carboxylate (9.0 g, 67% yield).

[1] Patent: WO2014/145004, 2014, A1. Location in patent: Paragraph 0103
[2] Patent: WO2011/139891, 2011, A1. Location in patent: Page/Page column 59
[3] Patent: WO2013/78295, 2013, A2. Location in patent: Paragraph 00184