An air-stable chiral P,N-ligand/PdCl2 partner enables a highly enantioselective oxidative homocoupling of naphthylboronic acids/boronates only in an oxygen atmosphere

Abstract

A highly enantioselective oxidative homocoupling of naphthylboronic acids/boronates has been reported for the first time using an easily available chiral P,N-ligand/PdCl₂ partner only under an oxygen atmosphere. A series of axially chiral binaphthyls have been prepared in excellent enantioselectivities (92% ee to 99% ee) in all cases with acceptable yields (up to 73% yield). This protocol complements the Suzuki and Chan–Lam couplings. This enantioselective homocoupling is enabled by the discovery of the first air(oxygen)-stable chiral P,N palladium complex capable of functioning even at high temperatures – conditions that are incompatible with most existing chiral phosphine ligands. These findings could aid the design and screening of new air-stable, temperature-tolerant chiral phosphine complexes and expand their application in catalytic redox reactions.