Enantioselective Copper‐Catalyzed Intramolecular Phenolic OH Bond Insertion: Synthesis of Chiral 2‐Carboxy Dihydrobenzofurans, Dihydrobenzopyrans, and Tetrahydrobenzooxepines

Efficient: A copper-catalyzed enantioselective intramolecular insertion of carbenoids into phenolic O-H bonds has been developed. This method can be used for the synthesis of the title compounds in high yields and excellent enantioselectivities under mild and neutral conditions. NaBAr(F)=sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate.