Nickel-hydrogen-bonding-enabled, phosphine-ligand-tuned regiodivergent isomerization of olefins

Olefin isomerization has an important impact on organic synthesis, fine chemicals, and polymer chemistry. However, due to the small energy differences between various potential isomers, achieving regioselective isomerization remains a challenge. We report on the nickel-catalyzed divergent isomerization of olefins, which leads to the selective formation of either a kinetic or thermodynamic isomer, with the specific product determined by the choice of phosphine ligand. This double-bond chain-walking reaction is characterized by its mild conditions, broad substrate scope, good regioselectivity, high yields, gram-scale synthesis, and the availability of materials from commercial sources. The pairing of this isomerization with ethenolysis led to the formation of formal one-carbon-deletion products. Mechanistic studies emphasize the critical role of the phosphine ligand in governing the regioselectivity of the double- bond chain-walking reaction, and a distinctive nickel-hydrogen- bonding intermediate was pointed out to be key to the success of this transformation.