1,1,3,3-Tetraethoxypropane → 1-Methylpyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione

Participants

Reaction Steps

14.34 g (101.7 mmol) 6-amino-1-methyluracil and 26 mL (108 mmol) 1,1,3,3-tetraethoxypropane are dissolved in a mixture of 250 mL ethanol and 1 liter water and refluxed for 3 hours. After cooling down to room temperature, the precipitated intermediate is isolated by filtration washed with water and dried. 7.71 g of the condensation product of the acetal and the amino group is added to 12.5 mL concentrated sulfuric acid and the mixture is heated to 160° C. After cooling down to room temperature, the mixture is poured into 125 g ice. The crude product precipitates from the medium, is isolated by filtration, washed to neutral pH and dried. 4.84 g of the crude product is dissolved in 2 l refluxing methanol. 300 mL silicagel is added and the mixture is evaporated under reduced pressure. The crude product loaded onto the silicagel is purified by preparative column chromatography using chloroform/methanol 9:1. 3.49 g (19%) 1-methylpyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione is isolated (m.p. 277–285° C., Lit. 285° C.).

Provenance & Evidence