Pyridine → 1,3-Dimethyl-5-ethoxycarbonyl-2-thiobarbituric acid

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Reaction Conditions

Reaction Steps

155 g (0.9 mol) of 1,3-dimethyl-2-thiobarbituric acid, 88,3 g (1.12 mol) of pyridine and 9 g of 4-dimethylaminopyridine are dissolved in 660 ml of dichloromethane and the solution is cooled to 0° C. Then 102 g (0.94 mol) of ethyl chloroformate are added dropwise over 1 hour. The mixture is subsequently stirred for 12 hours at 0° C., then allowed to warm to room temperature and worked up after a further 7 hours as follows. 600 ml of dichloromethane are added and the solution is washed with three 1000 ml portions of water, dried over Na2SO4 and the solvent is evaporated off. The crude product is recrystallised from ethanol. Melting point 90°-93° C.

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