3-Butyl-1-(prop-2-en-1-yl)-3,9-dihydro-1H-purine-2,6-dione → Xanthine

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Reaction Steps

16 g (0.050 mole) of mercury (II) acetate are dissolved in 250 ml water. 12.4 g (0.05 mole) of 1-allyl-3-butyl xanthine (prepared as described above from 1-butyl-5-formylamino-6-aminouracil and allyl bromide) dissolved in 250 ml of THF are added dropwise with stirring over a period of 10 minutes. After a few minutes, a precipitate is formed. Stirring is continued for 30 minutes, after which the mixture is cooled in an ice bath. 68 ml of 3 N NaOH are added, followed by the dropwise addition of 60 ml of a freshly prepared 0.5 M solution of NaBH4 in 3 N NaOH. On completion of the addition, stirring is continued for another 15 minutes. The solution is neutralized to pH 4-5 with 6 N HC1 (approximately 60 ml), saturated with NaC1 and the xanthine extracted with dichloromethane (3×200 ml). The organic extract is dried and the solvent is evaporated: 12.9 g of crude product containing 20% of starting product. The products are separated by passing the mixture through a column of silica using chloroform as eluent for the starting product and chloroform/methanol (95/5) for the hydroxylated xanthine (9.5 g) . The xanthine is recrystallized twice from water: 8.5 g (64%); Mp. 157-158° C.

Provenance & Evidence