Enantioselective Carbene Insertion into O–Hof Phenols with Chiral Palladium/2,2′-Biimidazole Complexes

A highly enantioselective insertion of α-aryl-α-diazoacetates into the O–H bonds of phenols has been successfully developed by employing palladium/2,2′-biimidazole complexes as catalysts, furnishing the chiral α-aryl-α-aryloxyacetates with up to 98% ee and 97% yield. Furthermore, these chiral palladium/2,2′-biimidazole complexes have also exhibited a good performance in the asymmetric insertion of α-aryl-α-diazoacetates into the N–H bonds of carbazoles. It was noted that these protocols also represent the successful application of palladium complexes of axially chiral 2,2′-biimidazole ligands in asymmetric catalysis.