Organocatalyzed, Three‐Component Construction of Cyanopyrazoles Using Diazoacetonitrile

An organocatalyzed three‐component protocol using diazoacetonitrile to access a wide range of cyanopyrazole derivatives is reported here. This strategy, which proceeds through a piperidine‐catalyzed Knoevenagel condensation/formal [3+2] cycloaddition/dehydrocyanation sequence, provides an efficient route to construct dicyanopyrazoles from aldehydes, malononitrile, and diazoacetonitrile regioselectively. Interestingly, by engaging cyanoacetate and cyanoacetamide in this protocol, we could achieve cyanopyrazole esters and carboxamides.