Water as a Direct Proton Source for Asymmetric Hydroarylation Catalyzed by a Rh(I)-Diene: Access to Nonproteinogenic β²/γ²/δ²-Amino Acid Derivatives

A highly enantioselective rhodium-catalyzed intermolecular hydroarylation of α-aminoalkyl acrylates using water as a direct proton source has been realized by employing a chiral bicyclo[3.3.0] diene ligand, allowing efficient access to a broad range of α-aryl-methyl-substituted β2-, γ2-, and δ2-amino esters with excellent enantioselectivities (up to 98% ee) under exceptionally mild conditions. By utilizing this method, a series of structurally interesting benzo-fused heterocyclic molecules and the corresponding β2-, γ2-, and δ2-amino acids are facilely constructed.