Gold(I)-Catalyzed Enantioselective Ring Expansions of Allenyl Cyclopropanols and Cyclobutanols

Herein, we report enantioselective gold(I)-catalyzed ring expansions of allenyl cyclopropanols and allenyl cyclobutanols. Cyclobutanones and cyclopentanones bearing vinyl-substituted quaternary chiral centers are formed in good yields and with excellent enantiomeric excesses. Efficient chiral inductions are achieved via asymmetric gold-ligand cooperation, which is enabled by chiral bifunctional phosphine ligands. This reaction employs a low catalyst loading and proceeds under mild reaction conditions. With a substrate possessing an additional prochiral center, an additional chiral center was set up with excellent diastereoselectivity, demonstrating the synthetic utility of this chemistry in accessing structures of increasing stereochemical complexity.