Enantioselective Ring-Opening Reactions of Racemic Ethynyl Epoxides via Copper−Allenylidene Intermediates: Efficient Approach to Chiral β-Amino Alcohols

Enantioselective copper-catalyzed ring-opening reactions of racemic ethynyl epoxides with amines using (R)-DTBM-MeO-BIPHEP as a chiral ligand have been found to give the corresponding amino alcohols in high yields with up to 94% ee. The reaction is considered to proceed via copper−allenylidene complexes as key intermediates. This methodology may provide a novel synthetic approach to optically active amino alcohols, the structures of which are widely found in many natural products, biologically active compounds, and chiral ligands.