Synthesis of 3-azoindoles

Azo compounds are an important class of organic colorants which consist of a conjugated chromophore azo (-N=N-) group in association with one or more aromatic or heterocyclic systems]. Azo dyes based on heterocyclic amines have higher tinctorial strength and give brighter dyeing than those derived from aniline based diazo components. Literature survey reveals that not much work has been done on N-alkyl 3-azoindoles and their pharmacological activity. It has been considered worthwhile to synthesise N-methyl-3-azoindoles as part of our ongoing research on the development of novel synthetic route for pyrrolo(3,2-b)indoles. We herein report a simple procedure for the synthesis of 3-azoindoles.