The Knoevenagel condensation between ethyl 4- chloroacetoacetate and aromatic aldehydes in ionic liquids

The Knoevenagel condensation is an important C=C bond formation in organic synthesis. Among possible solvents, refluxing benzene or toluene are common choices, 1 and removal of water from the reaction medium is typically done by means of a Dean-Stark trap. To avoid the use of hazardous organic solvents and relatively high temperatures, we were interested in the use of ionic liquids as potential solvents for this condensation. In the course of our studies towards the synthesis of chiral halogenated β-hydroxyesters, we were particularly interested in the reaction between ethyl 4-chloroacetoacetate and different aromatic aldehydes to produce the corresponding 2chloroacetyl-3-arylpropenoates.