Heterocyclic systems containing bridgehead nitrogen atom:: Synthesis and antimicrobial activity of imidazo [2,1-b]-1,3,4-thiadiazolo [2,3-c]-s-triazoles, s-triazolo [3,4-b]-1,3,4-thiadiazolo [3,2-b] imidazo [4,5b] quinoxaline and bis-(s-triazolo [3,4-b]-1,3,4-thiadiazolo [3,2-b] [imidazo [4,5-b] cyclohexane]-5a, 6a-diene)

Condensation of 4-amino-5-mercapto-3-(o-tolyl)-s-triazole 1 with cyanogen bromide gives 6-amino-3-(o-tolyl)-s-triazolo [3,4-b]-1,3,4-thiadiazole 2 which on condensation with chloranil yields 3,9-di-(o-tolyl)-6,14-dioxo-bis- (s-triazolo [3,4-b]-1,3,4-thiadiazolo [3,2-b] [imidazo] [4,5-b] cyclohexane-5a, 6a-diene) 3. 3-(o-Tolyl)-s-triazolo [3,4-b]1,3,4-thiadiazolo [3,2-b] imidazo [4,5-b] quinoxaline 4 was obtained by a similar condensation of 2 with 2,3-dichloroquinoxaline. The reaction of 2 with alpha-haloketones followed by bromination affords 7-aryl-3-(o-tolyl) imidazo [2,1-b]-1,3,4-thiadiazolo [2,3-c]-s-triazoles 5 and their 6-bromo analogues 6 respectively. The antibacterial and antifungal activities of some of the compounds have also been evaluated.