5-Aminouracil → 2499-96-9

Participants

Reaction Steps

Into a 2000-mL 4-necked round-bottom flask was placed a solution of 5-aminopyrimidine-2,4(1H,3H)-dione 1 (217 g, 1.71 mol, 1.00 equiv) in HCl (20%, 1302 mL), then added (E)-but-2-enal (143.5 g, 2.05 mol, 1.20 equiv). The resulting solution was heated to reflux for 3 h (hours) in an oil bath. The reaction mixture was cooled and filtered. The filtrate was concentrated under vacuum. The residual solution was diluted with 250 mL of water and adjusted to pH 10 with ammonia (25%). The isolated solid was collected by filtration, then washed with 2×100 mL of water, 2×250 ml of ethanol and 3×500 mL of ether and finally dried in an oven. This resulted in 63 g (21%) of 6-methylpyrido[3,2-d]pyrimidine-2,4(1H,3H)-dione 2. 1H-NMR (400 MHz, CD3OD, ppm): 7.56 (2H, s), 2.60 (3H, s)

Provenance & Evidence