合成路线1

N,N'-Bis(cyclopropylmethyl)urea (II) was prepared by the action of phosgene on cyclopropylmethylamine (I). Cyclization of urea (II) with cyanoacetic acid (III) in hot acetic anhydride produced the 6-aminouracil (IV). Subsequent nitrosation of (IV) by means of sodium nitrite and formic acid afforded the 5-nitroso derivative (V), which was further reduced to the 5,6-diaminouracil (VI) with sodium dithionite. Formylation of diamine (VI), followed by cyclization of the intermediate formamide (VII), gave rise to 1,3-bis(cyclopropylmethyl)xanthine (VIII). Nitration of xanthine (VIII) with HNO3 in acetic acid yielded the 8-nitro derivative (IX), which was finally reduced to the corresponding amine employing either tin and HCl or sodium dithionite.