Three-component cascade reaction of 3-ketonitriles, 2-unsubstituted imidazole N -oxides, and aldehydes.

A three-component condensation of 2-unsubstituted imidazole N -oxides, 3-ketonitriles, and aldehydes is described. The reaction proceeds via sequential Knoevenagel condensation/Michael addition under mild, catalyst-free conditions with various substrates. Furthermore, the corresponding 2-functionalized imidazole N -oxides can be further dehydrated to ( Z )-2-aroyl-3-(1 H -imidazol-2-yl)-acrylonitriles, which may also be directly prepared by changing the reaction conditions as a cascade of Knoevenagel condensation/Michael addition/dehydration.