Synthesis of Catalyst Using Bio‐benign Precursors and Its Application in One‐Pot Catalytic Synthesis of Imidazo[1,2‐a]pyridines

Abstract

AbstractDevelopment of catalysts using natural feedstock is the need of the current era, and accordingly, we have developed a new ligand N‐(2‐hydroxynapthylidene)‐L‐leucienyl‐4,6‐O‐ethylidene‐β‐D‐glucopyranosylamine using natural occurring D‐glucose and L‐amino acid. It interacts with several bio‐relevant metal ions like iron, copper, zinc, etc., but its association with cupric ions is immune to pH (4.2–9.1) change. In‐situ copper‐catalyzed reactions have been proven to be pivotal in many important organic syntheses, including imidazo[1,2‐a]pyridines, which is one of the important precursors of many drug molecules. Catalytic synthesis of imidazo[1,2‐a]pyridines requires high catalyst loading, hazardous solvent, high temperature, and long reaction time, which are major drawbacks towards green synthetic methodology. Interestingly, our glycoconjugate‐derived cupric complex catalyzes the reactions among aldehydes, 2‐aminopyridines, and terminal alkynes under the solvent‐free condition to afford one‐pot synthesis of imidazo[1,2‐a]pyridines and 23 derivatives have been reported in good to excellent yields (53–93 %) using lower reaction time, temperature, and catalyst loading compared to other reports on similar reactions. Hence, our approach enhances the green methodology towards the catalytic synthesis of imidazo[1,2‐a]pyridine derivatives.