Nano ZSM-5 Catalyzed Groebke Condensation: An Efficient Protocol for the Synthesis of 3-Aminoimidazo[1,2-a]pyridines

The imidazo [1,2] annulated nitrogen heterocycles bearing pyridine, pyrimidine, and pyrazine moieties constitute an important class of biologically active compounds such as sedative-hypnotic drugs Alpidem and Zolpidem. In 1998, an isocyanide-based multi component reactions (I-MCRs) was reported for the synthesis of imidazo[1,2]azines by condensation of an aldehyde, an isocyanide, and a 2-aminoazine [1]. Several methods have been developed for the synthesis of imidazoazines via above I-MCRs in the presence of the [bmim]Br ionic liquid, bio-supported catalyst cellulose sulfuric acid, p-toluenesulfonic acid, silica sulfuric acid, ammonium chloride, or tin(II) chloride at room temperature [2]. In this work,the ability of nano zsm-5 as an acid catalyst to promote the three-component condensation reaction from a diversity of aromatic aldehydes 1, 2-aminopyridines 2, and isonitriles 3 at room temperature is described. This methodology affords a number of 3- aminoimidazo [1,2] pyridines 4 in the presence nano zsm-5 (Figure 1) as a new and mild acid catalyst in the multi-component reaction in reasonable yields and short reaction time without any significant optimization of the reaction conditions.