PURPOSE: To prepare a pyridopyrimidine derivative useful as a drug, in high yield, by reacting a specific pyrimidinoaminomethylenemalonic acid cyclic ester with polyphosphoric acid in the presence of phosphorus pentoxide or phosphorus oxychloride.
CONSTITUTION: For example, the pyrimidinoaminomethylenemalonic acid cyclic ester of formulaI(R1 and R2 are hydrocarbon group, hydrocarbon groups connected with each other, or nitrogen-containing hydrocarbon group; R3WR5 are hydrocarbon group){e.g. N-ethyl-N-[2-(4-benzyl-1-piperazinyl)-pyrimidinyl]aminomethylenemalonic acid isopropylidene ester}obtained by the reaction of an alkoxymethylenemalonic acid cyclic ester with 2,4-diamino-substituted pyrimidine compound, is made to react with a polyphosphoric acid in the presence of phosphorus pentoxide and/or phosphorus oxychloride at 20W250°C to obtain the objective pyridopyrimidine derivative of formula II{e.g. 2-(4-benzyl-1-piperazinyl)-8-ethyl-5, 8-dihydro-5-oxopyrido[2,3-d]pyrimidine-6-carboxylic acid}.
KIHARA NORIAKI
TAKAHASHI SHIGERU
ISAYAMA SHIGERU
| JPS488800A | ||||
| JPS52139094A | 1977-11-19 |