Enantioselective Copper-Catalyzed Intramolecular Phenolic OH 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 (see scheme). NaBArF=sodium tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate. [ABSTRACT FROM AUTHOR]