Diethyl Sulfate → Pipemidic Acid

Participants

Reaction Steps

To a solution of 1.5 g of 5,8-dihydro-2-(1-piperazinyl)- 5-oxopyrido[2,3-d]pyrimidine-6-carboxylic acid in 60 ml of a 10% aqueous solution of sodium carbonate was added three 10 ml portions of diethyl sulfate. After completion of the reaction, the resulting mixture was neutralized with acetic acid. The precipitate was collected and recrystallized from dimethylformamide to give 0.8 g of 2-(1-piperazinyl)-5,8-dihydro-8-ethyl-5-oxopyrido[2,3-d]pyrimidine-6-carboxylic acid (compound 1) m.p. 253° - 255°C. Concentration of the mother liquor to about a half volume gave another solid which was further recrystallized from the same solvent to give 0.6 g of 2-(4-ethyl-1-piperazinyl)-5,8-dihydro-8-ethyl-5-oxopyrido[2,3-d]pyrimidine-6-carboxylic acid (compound 21), m.p. 228° - 230°C.

Provenance & Evidence