SYNTHESIS OF SOME NEW IMIDAZOLIUM AND PURINIUM SALTS AND THEIR RELATED DERIVATIVES

Cyclization of 5-amino-1-(4-methoxyphenyl) imidazole-4-carbonitrile 3 with formamide afforded 6-aminopurine derivative 4. When the latter was reacted with alkyl iodides, the purinium iodide salts 7a-c were obtained. Upon treating the salts 7a-c with a - kali, the dequaternized and rearranged products N-alkyl-9-(4-methoxyphenyl)-6-amino-9H-purina 8a-c were obtained. The 5- (methoxymethylideneamino) imidazole-4- carbonitrile 10 was synthesized by reacting 3 with trimethyl orthoformate. When the imidate 10 reacted with alkylamines, the corresponding 1-alkyl-9- (4-methoxyphenyl)-6-imino-9H-purines 1la-c were obtained. Rearrangement of the products 11a-c to their N-alkyl-6-amino-9H-purines 8a-c was carried out. The 3-alkylimidazolium-4-carbonitrile iodides 12a-e were synthesized by quaternizing product 3 with alkyl iodides. Treatment of the salts 12a-e with alkali, afforded the ring-opened products : 2-amino-2-(4-methoxyphenylamino)-1-N-alkyl formylaminoethylene-1-carbonitriles 13a-e, rather than the expected 1-alkyl-4-(4-methoxyphenylamino) imidazole-5-carbonitriles 14a-e. Products 14a-e were obtained by cyclization of 13a-e in acidic medium.