Dicyclohexylcarbodiimide → 8-Cyclopentyl-3-propyl-3,7-dihydro-purine-2,6-dione

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Reaction Steps

To a suspension of 5,6-diamino-1-propyl-2,4(1H, 3H)pyrimidinedione (Japanese Published Unexamined Patent Application No. 57517/80) in 600 ml of dimethylformamide were sequentially added 17.7 ml (163 mmol) of cyclopentanecarboxylic acid, 30.0 g (196 mmol) of hydroxybenzotriazole and 50.5 g (245 mmol) of dicyclohexylcarbodiimide. The mixture was stirred at room temperature overnight. Insoluble materials were filtered off and the solvent was evaporated under reduced pressure After 600 ml of 4N aqueous sodium hydroxide solution was added to the residue, the mixture was refluxed for 10 minutes under heating. Under ice cooling, insoluble materials were filtered off and 50 ml of methanol was added to the filtrate. After neutralization with conc. hydrochloric acid, the precipitate was collected by filtration to afford 28.3 g (yield, 66%) of Compound c.

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