Copper-catalyzed cyanoisopropylation of beta-keto esters using azos: synthesis of beta-dicarbonyls bearing an alfa-tertiary nitrile moiety

A copper-catalyzed α-cyanoisopropylation reaction of β-keto esters using azo compounds as cyanoalkylating agents is presented, providing an easy access to β-dicarbonyls containing an α-tertiary nitrile moiety with adjacent tertiary and quaternary carbon centers. It is remarkable because a tremendous steric conflict is involved during reaction. Such nitriles were otherwise unavailable, and the reaction features simple and relatively mild conditions and good functional-group tolerance.