Dimethyl Sulfoxide → 9-(phenyl-amino)-6-methyl-4-oxo-6,7-dihydro-4H-pyrido[1,2-a]pyrimidine-3-carboxylic acid ethyl ester

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Reaction Steps

40.0 g. (0.127 mole) of 9-bromo-6-methyl-4-oxo-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidine-3-carboxylic acid ethyl ester are dissolved in 80 ml. of dimethylsulfoxide and 26 ml. (0.285 mole) of aniline are added. The solution is allowed to stand at room temperature for 3-4 days. The mixture is then diluted with 100 ml. of water, shaken out with 3×50 ml. of benzene. The combined organic layers are dried with calcinated sodium sulfate and evaporated in vacuo. The residue is recrystallized from ethanol and thus 24.5 g. (59.3%) of 9-(phenyl-amino)-6-methyl-4-oxo-6,7-dihydro-4H-pyrido[1,2-a]pyrimidine-3-carboxylic ethyl ester is obtained, melting point: 119°-120° C.

Provenance & Evidence