Ligand-centered redox driven Zn(II)-catalyzed anti-markovnikov hydroamination of activated alkenes with primary aromatic amines via aminium radical cations

Abstract

A ligand-centered redox-driven strategy for anti-Markovnikov hydroamination of electron-deficient alkenes including acrylates, acrylonitrile, and acrylamides-enabled by a well-defined Zn(II)-catalyst bearing a redox-active arylazo-phenanthroline ligand is reported.The azo-functionalized ligand serves as the key redox mediator, enabling single-electron transfer (SET) from primary aromatic amines to the low-lying π*-acceptor orbital of the ligand scaffold, generating aminium radical cation intermediates that engage in regioselective radical hydroamination under thermal conditions (100 ºC), circumventing the need for precious metals, external oxidants, or photochemical activation. The protocol demonstrates broad substrate scope and functional group tolerance, efficiently transforming a variety of amines, including heteroaryl, electron-rich, and complex amines derived from natural products, into valuable hydroaminated products. Mechanistic studies support a radical pathway initiated by SET to the azo-functionalized catalyst, with the redox-active ligand mediating all key electron-transfer events while the Zn(II)-center acts as a coordination scaffold. This work highlights the potential of redox-active ligand systems to enable sustainable radical pathways for C-N bond formation, introducing a new catalytic paradigm for the selective hydroamination of electron-deficient alkenes to access linear alkylamine frameworks.