Cascade Oxidative Coupling/Cyclization: A Gateway to 3‑Amino Polysubstituted Five-Membered Heterocycles

Taking
advantage of the coordinating activation strategy, we have
developed the cascade oxidative coupling/cyclization of α-C­(sp3)–H bonds of amines with enamines or β-keto esters
for the synthesis of three types of five-membered heterocycles. α-Amino
acids as the substrate lead to 3-amino 1,3-dihydro-2H-pyrrol-2-ones and furan-2­(3H)-ones by using air
or dioxygen as the sole clean oxidant, respectively. α-Amino
ketones give a range of 3-amino 1H-pyrroles by using
di-tert-butyl peroxide as the oxidant. A three-component,
one-pot reaction from readily available amine, β-keto ester,
and α-amino ketone enhances the practicality of the modular
construction of 1H-pyrrole scaffolds. This programmed
protocol features simple reaction conditions, readily available starting
materials, broad substrate scope, and high functional group tolerance.