Asymmetric (CpRh)-Rh-x(III)-Catalyzed Acrylic Acid C-H Functionalization with Allenes Provides Chiral gamma-Lactones

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