Metal‐Free Activation of DMF by Dioxygen: A Cascade Multiple‐Bond‐Formation Reaction to Synthesize 3‐Acylindoles from 2‐Alkenylanilines

A cascade C-N, C-C and C-O multiple-bond-formation reaction to synthesize 3-acylindoles from 2-alkenylanilines with DMF (N,N-dimethylformamide) as a one-carbon synthon is described. This approach employed dioxygen as a terminal oxidant and oxygen donor, generally provided the 3-acylindoles in moderate to good yields. Moreover, the mechanistic investigation unambiguously revealed that the 2-carbon of 3-acylindole was derived from the N-methyl group of DMF.