Hydrochloric Acid → Ethyl 8-allyl-5-hydroxy-7-oxo-2-phenyl-7,8-dihydropyrido[2,3-d]pyrimidine-6-carboxylate

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Reaction Steps

To a 50 ml. solution of NaOEt (0.3 g. Na-0.013 mole) was added 2.08 g. (0.013 mole) of diethyl malonate and this was stirred 10 minutes, then stripped to dryness. DMF was added to form a solution and then 1.85 g. (0.0065 mole) of 1-(2-propenyl)-7-phenyl-2H-pyrimido[4,5-d][1,3]oxazine-2,4(1H)-dione was added and heated at reflux for 1.5 hours. When cool, the reaction was poured into dilute HCl and the resulting precipitate collected on a filter and rinsed with water. Recrystallization from ethyl acetate gave 1.0 g. of product--m.p. 177°-180° C.

Provenance & Evidence