Asymmetric CpxRh(III)-Catalyzed Acrylic Acid C–H Functionalization with Allenes Provides Chiral γ‑Lactones

A chiral cyclopentadienyl (Cpx) ligand featuring the semi-saturated H8-binaphthyl backbone as the chiral element was developed. Its application potential was demonstrated by CpxRhIII-catalyzed C–H bond functionalization of acryl acids and allenes, exhibiting superior catalytic performance compared to other Cpx ligands. The outlined enantioselective [4 + 1]-annulation process results in synthetically attractive α,β-unsaturated γ-lactones having an allylic stereogenic center, which were obtained in enantioselectivities of up to 99:1 enantiomeric ratio.