N−SO3H Functionalised Brønsted Acidic Ionic Liquid Catalysed Sequential One‐Pot Synthesis of 2‐Amino‐3‐Cyanopyridines via Claisen‐Schmidt Condensation Under Solvent‐free Condition

Abstract

AbstractThis work presents a simple approach for the synthesis of 2‐amino‐3‐cyanopyridines via a one pot two‐step sequential route catalysed by direct N‐−SO3H functionalised Brønsted acidic ionic liquids (BAILs). Herein, catalytic activities of four BAILs namely ([TSPi][Cl]2, [DSIM][TFA], [EDSIM][TFA] and [DBDSA][TFA]) were explored and among them [TSPi][Cl]2 was found to be the most efficient reusable homogeneous catalyst. This process involves the ionic liquid catalysed in situ generation of chalcones from Claisen‐Schmidt condensation between aromatic aldehydes and acetophenone/4‐Cl acetophenone, followed by multicomponent reaction (MCR) with malononitrile and ammonium acetate using the same IL catalyst to selectively produce 2‐amino‐3‐cyanopyridine derivatives in a solvent‐free medium at 80 °C within 30–60 minutes in high yields (96–86 %). This amalgamation of MCR with ionic liquids and solvent‐free conditions makes the present work more compliant with the protocols of Green Chemistry.