Well-Defined Chiral Copper NHC Complex in the Asymmetric Conjugated beta-Borylation and One-Pot Metathesis-Asymmetric beta-Borylation Reactions

Highly stereoselective conjugate beta-borylation, using a new chiral NHC-based copper catalyst, has been achieved. The chiral NHC copper complex was prepared in gram scale and showed high enantioselectivity and activity (up to 10000 turnovers at 100 ppm of catalyst loading). This method was employed in the synthesis of a chiral beta-borylated ester from simple unconjugated alkenes though an unprecedented one-pot cross metathesis-asymmetric borylation sequence.