Nickel-Catalyzed Reductive Alkylation of Aldimines with Unactivated Alkyl Iodides

A nickel-catalyzed reductive alkylation of directing-group-free N-sulfonyl and N-aryl aldimines is reported. The reaction proceeds at ambient temperature and accommodates unactivated primary, secondary, and tertiary alkyl iodides as well as selected activated alkyl bromides with broad functional-group tolerance. Complex molecule-derived alkyl iodides, a gram-scale reaction, and β-amino ester derivatizations demonstrate synthetic utility. Mechanistic studies support nickel-mediated generation of a solution-accessible alkyl radical and are consistent with outer-sphere radical addition to the imine.