Sustainable Photoelectrochemical Activation of Acetonitrile via Transient Alkynylnitrile Intermediates

Abstract

Direct functionalization of acetonitrile remains a long-standing challenge due to the exceptional stability of its C(sp³)-H bonds. Herein we report a sustainable photoelectrochemical strategy that enables the direct activation of acetonitrile and its transformation into β-N-substituted enaminonitriles under mild and oxidant-free conditions. This process employs a synergistic light-electricity input to promote hydrogen-atom transfer initiation followed by anodic oxidation, generating a transient alkynylnitrile intermediate in situ. The highly reactive intermediate is efficiently intercepted by a range of amines to afford β-N-substituted enaminonitriles in good yields. The transformation proceeds at room temperature without the use of external chemical oxidants or strong bases, highlighting the advantages of photoelectrochemical catalysis as a green activation platform. Mechanistic investigations, including isotopic labeling experiments, in situ infrared spectroscopy, and DFT calculations, support the formation of the alkynylnitrile intermediate and elucidate the underlying reaction pathway.The method exhibits broad substrate scope and is applicable to the late-stage functionalization of amino acids and short peptides. This work demonstrates a sustainable strategy for converting a common solvent into a versatile synthetic building block and showcases the potential of photoelectrochemical catalysis for enabling challenging C-H functionalization processes.