Rh(III)‐Catalyzed Enantioselective Intermolecular Aryl C—H Bond Addition to Aldehydes

Comprehensive Summary The direct addition of aryl C—H bond to carbon‐heteroatom double bond by transition‐metal‐catalyzed C—H activation has been extensively investigated in the past decade. However, the enantioselective intermolecular C—H addition to aldehyde has not yet been reported and is of significant challenge. Rh(III)‐catalyzed highly enantioselective intermolecular C—H addition of aryl oxime ethers to glyoxylates is reported. Chiral mandelic acid esters were obtained in excellent yields (up to 98%) and enantioselectivity (up to 99% ee) in the presence of a chiral CpRh(III) catalyst under mild conditions. The substituents on the Cp ring and BINOL skeleton were responsible for the high enantioselectivity observed. The method displays a broad substrate scope and good functionality tolerance. These results provide not only a promising C—H addition approach but also a proof of concept for developing broader asymmetric C—H addition reactions.