Sodium methanolate methanol → 2-Methoxypyrido[2,3-d]pyrimidin-7(8H)-one

To a solution of 0.87 g of ethyl (2E)-3-(4-amino-2-methoxypyrimidin-5-yl)acrylate in 50 mL of methanol, 2.31 g of a 28% sodium methoxide/methanol solution was added at room temperature, and the mixture was heated under reflux while stirring for 4 hours. The reaction mixture was cooled to room temperature, and the solvent was then distilled off under reduced pressure. To the resultant residue, a saturated aqueous ammonium chloride solution and chloroform were added, the organic layer was separated, and the aqueous layer was extracted with chloroform. The organic layer and the extract were combined, the resultant solution was dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. The solid thus obtained was washed with diethyl ether to obtain 0.55 g of 2-methoxypyrido(2,3-d)pyrimidin-7(8H)-one as a yellow solid.