Nickel-Catalyzed β-Methyl Vinylation Using Allylamine as a Masked Alkenyl Electrophile

Abstract

Direct activation of native C(sp2)–NH2 bonds in alkenyl amines remains a largely unmet challenge in cross-coupling chemistry owing to their high bond dissociation energies, poor leaving-group ability, and competing tautomerization pathways. Herein, we report a nickel-catalyzed tandem deaminative coupling/alkene isomerization that bypasses these limitations, converting allylamine and arylboronic acids directly into (E)-β-methyl vinylarenes in a single base-free operation. Density Functional Theory (DFT) calculations reveal that DPEphos facilitates the key migratory insertion step, while deuterium-labeling experiments support a mechanism in which boronic acid initiates isomerization through formation of an active Ni–H species, followed by a net 1,3-hydrogen shift without requiring stoichiometric involvement of boronic acid. The method accommodates electronically diverse arylboronic acids and is readily performed on gram scale, providing a practical and stereoselective alternative to conventional olefination approaches.