Synthesis, anticonvulsant and analgesic activities of some 6-substituted imidazo(2,1-b)-1,3,4-thiadiazole-2-sulfonamides and their 5-bromo derivatives.

A series of 6-substituted imidazo(2,1-b)-1,3,4-thiadiazole-2-sulfonamides (V) were prepared by condensation of 2-amino-1,3,4-thiadiazole-5-sulfonamide (II) with an appropriate 2-bromo-ketone (III). Bromination of V in glacial acetic acid gave the corresponding 5-bromo derivatives (VI). Five selected compounds (15-18 and 28) were evaluated for their anticonvulsant and analgesic activities. Compounds 15-17 showed maximum protection (83%) against pentylene tetrazole induced convulsions and maximum electroshock induced seizures while the standard phenobarbital sodium and phenytoin sodium showed 100% protection, respectively. Compounds 15, 16 and 18 showed superior analgesic activity to acetylsalicylic acid in rat caudal immersion test.