The reactions of substituted benzothiazol-2-ylhydrazones with bromine: a route to s-triazolo[3,4-b][1,3]benzothiazoles

Abstract

The products of the reaction of p-substituted benzaldehyde benzothiazol-2-ylhydrazones with bromine depended on the molar ratio of the reactants and the reaction time. With 1 mol of bromine and short reaction times hydrazone bromonium bromides and perbromides were formed. With 0·5 mol of bromine and longer reaction times the products included hydrobromides, hydrazonyl bromides, and 6 -bromobenzothiazol-2-ylhydrazones. Cyclisations of the hydrazonyl bromides were investigated and as well a single-step cyclisation of the parent hydrazones with bromine was developed as an efficient cyclisation route to s-triazolo[3,4-b][1,3]benzothiazoles.