Heterocyclic systems containing bridgehead nitrogen atom:: Synthesis and bioactivity of thiazolo[3, 2-b]-s-triazoles and isomeric thiazolo[2, 3-c]-s-triazoles

The reaction of 3-[p-(t-butyl phenyl)]-5-mercapto-s-triazole 2 with alpha -haloketones gives, in two steps, 5-substituted-2-[p-(t-butyl phenyl)] thiazolo[3, 2-b]-s-triazoles 4 and not the isomeric 5-substituted-3-[p-(t-butyl phenyl)] thiazolo[2, 3-c]-s-triazoles 6. Unequivocal synthesis of the latter has also been achieved by condensing 1-[p-(t-butylbenzoyl)]-3-thiosemicarbazide 1 with alpha -haloketones, which furnishes in first step, 2-[p-(t-butylbenzoyl)]hydrazino-4-(substituted phenyl)thiazole hydro-bromides 5 and not the alternative 2-[p-(t-butyl benzoyl)]hydrazino-5-(substituted phenyl) thiazole hydrobromides. The former compounds, on treatment with phosphoryl chloride undergo facile cyclization to yield 6. Their antibacterial and antifungal activities have also been studied.