SYNTHESIS AND ANTICONVULSANT ACTIVITY OF 3H-IMIDAZO[4,5-C]PYRIDAZINE,1H-IMIDAZO[4,5-D]PYRIDAZINE AND 1H-BENZIMIDAZOLE ANALOGS OF 9-(2-FLUOROBENZYL)-6-METHYLAMINO-9H-PURINE

The 3H-imidazo[4,5-c]pyridazine, 1H-imidazo[4,5-d]pyridazine, and 1H-b enzimidazole analogues of the potent anticonvulsant purine 9-(2-fluoro benzyl)-6-methylamino-9H-purine (1, 78U79) were synthesized and tested for anticonvulsant activity. The 3H-imidazo[4,5-c]pyridazines 8 and 9 were prepared in five stages from 3,4,5-trichloropyridazine (2). The 1H-imidazolo[4,5-d]pyridazine 15 was synthesized in four stages from t hyl]-1,5-dihydro-4H-imidazo[4,5-d]pyridazin-4-one (10a). The benzimida zole analogues 18 and 20 were prepared from 2,6-dinitroaniline in thre e stages. These compounds were one-tenth or less as active as 1 in pro tecting rats against maximal electroshock-induced seizures.