Nickel-Catalyzed Regio- and Stereoselective Hydroalkylation of Allenes: Exploiting the Unique Reactivity of Diazo Compounds as an Alkylating Source

The reactivity of allenes has historically been limited with no previous examples of their hydroalkylation using diazo compounds in any transition-metal catalytic framework. In this study, we present a Ni-catalyzed regio- and stereoselective hydroalkylation reaction of allenes utilizing diazo compounds as alkylating agents. The success of this method can be attributed to the use of a pyridine-based P,N ligand, which combines the advantages of both phosphine and nitrogen ligands. Additionally, the carbonyl group in the diazo compound facilitates the formation of stable intermediates. Our detailed mechanistic studies reveal that the reaction proceeds through an initial interaction with the diazo compound, followed by engagement with the allene.