反应详情

10.0 g. (31.83 mmoles) 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 100 ml. anhydrous ethanol. 6.9 ml. (63.66 mmoles) of N-methylaniline are added to the solution, whereafter the reaction mixture is boiled under reflux for 8 hours. When the reaction is completed the solvent is distilled off at reduced pressure. To the residue 100 cm3 5% by weight aqueous solution of hydrochloric acid is added followed by extraction of the product twice with 30 ml. chloroform. The combined organic layers are dried above calcinated sodium sulfate and evaporated in vacuo. The residue is dissolved in 25 cm3 of methanol and allowed to stand overnight in a refrigerator. The precipitated crystals are filtered and washed with some methanol. 2.8 g. (25.9%) of 9-(N-methyl-anilino)-6-methyl-4-oxo-6,7-dihydro-4H-pyrido[1,2-a]pyrimidine-3-carboxylic acid ethyl ester is obtained which after recrystallization from methanol melts at 131°-133° C.

1. temperatureunder reflux for 8 hours
2. distillationis distilled off at reduced pressure
3. additionTo the residue 100 cm3 5% by weight aqueous solution of hydrochloric acid is added
4. extractionfollowed by extraction of the product twice with 30 ml
5. customThe combined organic layers are dried
6. customevaporated in vacuo
7. dissolutionThe residue is dissolved in 25 cm3 of methanol
8. filtrationThe precipitated crystals are filtered
9. washwashed with some methanol