Chiral Bipyridine Ligand with Flexible Molecular Recognition Site: Development and Application to Copper-Catalyzed Asymmetric Borylation of α,β-Unsaturated Ketones

A novel chiral bipyridine ligand bearing a flexible side chain with a molecular recognition site enables precise stereocontrol through the cooperative action of metal center and hydrogen bonds. This new chiral ligand was applied to the copper-catalyzed asymmetric borylation of α,β-unsaturated carbonyl compounds. The reaction afforded the corresponding borylated products in good yields with high enantioselectivities. Preliminary studies of the functional group-selective transformation revealed that the newly designed chiral bipyridine ligand has the potential to control chemo- and site selectivity in addition to stereoselectivity.