1,5-BENZODIAZEPINES .11. 5-(DIALKYLAMINO) OR 5-(ALKYLTHIO) SUBSTITUTED 8-CHLORO-6-PHENYL-6H-[1,2,4]TRIAZOLO[4,3-A][1,5]BENZODIAZEPINES WITH ANTICONVULSANT ACTIVITY

The cyclocondensation of (dimethylamino)benzodiazepinones 3a,b with hydrazides yielded triazolobenzodiazepinones 4 which were treated with Lawesson's reagent to give thiolactams 5. The phase-transfer catalyzed (TEBA) alkylation of compounds 5 with suitable alkyl halides afforded 5-(alkylthio)-6-phenyl-6H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepines 6a-f. The desired N,N-dialkyl-6-phenyl-6H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amines 7a-k were finally obtained from the reaction of the (methylthio)derivatives 6a-d with proper dialkylamines. Compounds 6b-f and 7a-e, g-k were screened for anticonvulsant activity after a preliminary evaluation of their gross behavioral effects and acute toxicity. Nine of the 15 triazolobenzodiazepines tested exerted a clear-cut anticonvulsant effect associated with low acute toxicity. In particular, the most active compounds 6e, f and 7h showed LD50/ED50 ratios that were notably higher than that of phenobarbital and ranging from 50% to 20% of that of diazepam, the latter used as reference drugs.