Gold(I)-Catalyzed Asymmetric Transformations of 1-(1-Alkynyl)cyclobutyl Ketones: Access to Enantioenriched Cyclopenta[ b ]furans Bearing Vicinal Bridged Quaternary Stereocenters
Present herein is a gold(I)-catalyzed asymmetric cascade reaction of 1-(1-alkynyl)cyclobutyl ketones. Upon activation by a chiral phosphoric-acid-tethered gold(I) complex, they undertake intramolecular 5-endo-dig cyclization, and the resulting oxocarbenium species engage in an asymmetric 1,2-alkyl migration to genera...