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

Abstract

The reaction of 3-[<i>p</i>-(<i>t</i>-butyl phenyl)]-5-mercapto-<i>s</i>-triazole <b>2</b> with α-haloketones gives, in two steps, 5-substituted-2-[<i>p</i>-(<i>t</i>-butyl phenyl)] thiazolo[3, 2-<i>b</i>]-<i>s</i>-triazoles <b>4</b> and not the isomeric 5-substituted-3-[<i>p</i>-(<i>t</i>-butyl phenyl)] thiazolo[2, 3-<i>c</i>]-<i>s</i>-triazoles <b>6</b>. Unequivocal synthesis of the latter has also been achieved by condensing 1-[<i>p</i>-(1-butylbenzoyl)]-3-

thiosemicarbazide <b>1</b> with α-haloketones, which furnishes in first step, 2-[<i>p</i>-(<i>t</i>-butylbenzoyl)] hydrazino-4-(substituted phenyl)thiazole hydro-bromides <b>5</b> and not the alternative 2-[<i>p</i>-(<i>t</i>-butyl<i> </i>benzoyl)]hydrazino-5-(substituted pheyl) thiazole hydrobromides. The former compounds, on treatment with phosphoryl chloride undergo facile cyclization to yield <b>6</b>. Their antibacterial and antifungal activities have also been studied.