Direct α‑Alkenylation of Cyclic Amines with Maleimides through Fe(III)-Catalyzed C(sp³)–H/C(sp²)–H Cross Dehydrogenative Coupling

Presented herein is a novel and efficient α-C­(sp³)–H alkenylation of cyclic amines with maleimides. Mechanistically, this C­(sp³)–H/C­(sp²)–H cross dehydrogenative coupling (CDC) reaction involves a cascade procedure including oxidative α-amino radical formation from the cyclic amine substrate and nucleophilic addition of the in situ formed α-amino radical onto the electron-deficient carbon–carbon double bond of maleimide followed by oxidation and β-elimination. Notably, this direct α-functionalization provides an effective alternative to the conventional ionic reaction mode, in which an imine or iminium intermediate is formed to react with electron-rich coupling partners other than electron-deficient ones. In general, this method features readily available and structurally diverse substrates, a green and economical catalyst, a unique reaction pathway, mild reaction conditions, high efficiency, and excellent atom economy. This new reaction enriches the application of Fe­(III)-catalyzed C­(sp³)–H activation and functionalization.