Aldol-type coupling of aldehydes with ethyl diazoacetate catalyzed by supported ionic liquid

Chloromethylated polystyrene supported ionic liquid is used as catalyst in the aldol-type coupling of a variety of aldehydes with ethyl diazoacetate in water. Moderate to excellent yields of the corresponding α-diazo-β-hydroxy esters were obtained. The catalyst was separated by filtration and reused in five consecutive cycles without any appreciable loss of activity.