Mechanism and Origins of Regio- and Stereoselectivities in Iridium-Catalyzed Isomerization of 1-Alkenes to trans-2-Alkenes.

Density functional theory calculations were performed to investigate the iridium-catalyzed isomerization of 1-alkenes to trans-2-alkenes. The computations show that the originally proposed π-allyl mechanism is kinetically unfeasible. A metal-ligand cooperative mechanism was suggested to account for the experimental results. The reaction was found to begin with the C(sp)-H oxidative addition of the pyridine ligand to give the Ir(III) hydride intermediate, from which the isomerization further takes place via the insertion/elimination pathway.