A chiral 6-membered N-heterocyclic carbene copper(I) complex that induces high stereoselectivity

A chiral 6-membered annulated N-heterocyclic (6-NHC) copper complex that catalyzes β-borylations with high yield and enantioselectivity was developed. The chiral 6-NHC copper complex is easy to prepare on the gram scale and is very active, showing 10,000 turnovers at 0.01 mol % of catalyst without significant decrease of enantioselectivity and with useful reaction rates.