Cyclopentylamine → 4H-Pyrido(1,2-a)pyrimidine-3-carboxamide, N-cyclopentyl-6-methyl-4-oxo-

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Reaction Steps

A mixture containing 16.32 g (0.08 mol) of 6-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxylic acid and 12.4 ml (0.088 mol) of triethylamine in 480 ml of chloroform is cooled below -10° C. by ice salt. A solution of 6.5 ml (0.08 mol) of methyl chloroformate in 40 ml of chloroform is dropped to the above mixture at -10° C. during 20 minutes. After stirring for 5 minutes, 7.49 g (0.086 mol) of cyclopentylamine dissolved in 80 ml of chloroform are dropped to the above solution at -15° C. during 30 minutes. The reaction mixture is stirred for 1 hour below -10° C., then allowed to stand overnight under cooling by ice. For working up, the reaction mixture is washed 3 times with 150 ml of 5% sodium hydrogen carbonate solution each, then 3 times with 150 ml of water each. The organic phase is dried over anhydrous sodium sulfate, filtered and evaporated to yield 14.3 g (65.9%) of the title product as yellow crystals after recrystallization from ethanol, m.p.: 158°-160° C.

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