Synthesis of Chiral Boron-bridged Anionic C2-symmetric Bisoxazolines and their Applications in Asymmetric Catalysis

Anionic boron-based chiral bisoxazoline ligands, the borabox ligands, are readily prepared from amino alcohols and haloboranes. The highly modular nature of these ligands allows both for electronic and steric tuning of the structure. The high enantioselectivities obtained in various Cu-catalyzed asymmetric reactions and especially in the kinetic resolution of pyridyl alcohols where bisoxazoline ligands exhibit almost no selectivity, point to a considerable potential of borabox ligands in asymmetric catalysis.