Regiodivergent and Diastereoselective CuH-Catalyzed Allylation of Imines with Terminal Allenes.

A copper-catalyzed, chemoselective hydrometalation process enables the use of simple allenes as allylmetal nucleophile surrogates in imine allylation reactions. By modulating the nitrogen-protecting group, either highly branched- or linear-selective addition can be achieved from the same allene. Both reactions exhibit excellent diastereoselectivity and broad functional-group tolerance. Preliminary results indicate that good enantioselectivity can also be achieved in the linear-selective reaction. Finally, a mechanistic model for the regiodivergence is proposed on the basis of density functional theory calculations.