Methyl chloroformate → 4H-Pyrido(1,2-a)pyrimidine-3-carboxamide, 9-methyl-4-oxo-N-propyl-

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Reaction Steps

A mixture containing 9.2 g (0.045 mol) of 9-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxylic acid and 7.05 ml (0.05 mol) of triethylamine in 280 ml of chloroform is cooled below -10° C. by ice-salt. A solution of 3.7 ml (0.045 mol) of methyl chloroformate dissolved in 25 ml of chloroform is dropped to the above mixture at -21° C. during 10 minutes. After stirring for 5 minutes, 2.95 g (0.05 mol) of propylamine dissolved in 50 ml of chloroform are dropped to the above solution at a temperature between -21° C. and -19° C. during 45 minutes. The reaction mixture is stirred below -10° C. for 1 hour, then allowed to stand overnight under cooling by ice. For working up, the reaction mixture is washed 3 times with 70 ml of 5% sodium hydrogen carbonate solution each, then 3 times with 70 ml of water each. The organic phase is dried over anhydrous sodium sulfate, filtered and evaporated to give 7.8 g (70.7%) of the named compound as snow-white crystals after recrystallization from ethanol, m.p.: 138°-140° C.

Provenance & Evidence