Asymmetric Alkenyl C−H Functionalization by Cp ^x Rh ^III forms 2 H ‐Pyrrol‐2‐ones through [4+1]‐Annulation of Acryl Amides and Allenes

An efficient Cp x Rh III ‐catalyzed enantioselective alkenyl C−H functionalization/[4+1] annulation of acryl amides and allenes is reported. The described transformation provides straightforward access to enantioenriched α,β‐unsaturated‐γ‐lactams bearing a quaternary stereocenter. The reaction operates under mild conditions, displays a broad functional‐group tolerance, and provides 2 H ‐pyrrol‐2‐ones with excellent selectivity of up to 97:3 er. Such scaffolds are frequently found in natural products and synthetic bioactive compounds and are of significant synthetic value. It is noteworthy that the allene serves as a one‐carbon unit in the [4+1]‐annulation.