Diastereoselective Synthesis of Pyrazolines using a Bifunctional Bronsted Acidic Ionic Liquid under Solvent-Free Conditions

An efficient protocol for the excellent diastereoselective synthesis of pyrazolines via a three-component reaction of aldehydes, hydrazines and dimethyl acetylenedicarboxylate (DMAD) in the presence of a bifunctional Bronsted acidic ionic liquid as a reusable catalyst under solvent-free conditions is reported. Easy work-up, short reaction times, high yields of the products and an environmentally benign procedure avoiding toxic organic solvents are other significant features of this method.