Asymmetric Alkenyl C-H Functionalization by CpxRhIII forms 2H-Pyrrol-2-ones through [4+1]-Annulation of Acryl Amides and Allenes

An efficient (CpRhIII)-Rh-x-catalyzed enantioselective alkenyl C-H functionalization/[4+1] annulation of acryl amides and allenes is reported. The described transformation provides straightforward access to enantioenriched alpha,beta-unsaturated-gamma-lactams bearing a quaternary stereocenter. The reaction operates under mild conditions, displays a broad functional-group tolerance, and provides 2H-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.