Cyclopentylamine → 4H-Pyrido(1,2-a)pyrimidine-3-carboxamide, N-cyclopentyl-8-methyl-4-oxo-

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Reaction Steps

A mixture containing 1.22 g (0.006 mol) of 8-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxylic acid and 0.84 ml (0.006 mol) of triethylamine in 40 ml of chloroform is cooled below -10° C. by ice-salt. A solution of 0.46 ml (0.006 mol) of methyl chloroformate in 3 ml of chloroform is dropped to the above mixture at -15° C. during 10 minutes. After stirring for 5 minutes, 0.56 g (0.0066 mol) of cyclopentylamine dissolved in 6 ml of chloroform is dropped to the above solution. The reaction mixture is stirred at -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 15 ml of 5% sodium hydrogen carbonate solution each, then 3 times with 15 ml of water each. The organic phase is dried over anhydrous sodium sulfate, filtered and evaporated to yield 0.9 g (55%) of the named compound as a crystalline substance after recrystallization from ethanol, m.p.: 220°-222° C.

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