Dimeric TADDOL Phosphoramidites in Asymmetric Catalysis: Domino Deracemization and Cyclopropanation of Sulfonium Ylides

A gold-catalyzed asymmetric cyclopropanation of unactivated olefins with sulfonium ylides in the presence of a bimetallic catalyst with a novel dimeric TADDOL-phosphoramidite ligand is reported. This transformation allows a rare gold-catalyzed dynamic deracemization of chiral racemic substrates, where the same catalyst is responsible for several synergistic tasks in solution. The products are useful building blocks in synthesis and enable expeditious access to natural products.