Chiral Cyclometalated Oxazoline Gold(III) Complex-Catalyzed Asymmetric Carboalkoxylation of Alkynes

Asymmetric catalysis by using novel chiral O,O'-chelated 4,4'-biphenol cyclometalated oxazoline gold(III) complexes has been developed. A high yield (<= 89%) and a high enantioselectivity (<= 90% ee) were achieved in asymmetric carboalkoxylation of alkynes. Enantioselectivity could be significantly improved from 19% to 90% ee by increasing the steric size of the substituent on the chiral oxazoline ligand. Catalytically active Au-III species and the origin of chiral induction are proposed.