Vaulted Biaryls in Catalysis: A Structure-Activity Relationship Guided Tour of the Immanent Domain of the VANOL Ligand

The active site in the BOROX catalyst is a chiral polyborate anion (boroxinate) that is assembled in situ from three equivalents of B(OPh)(3) and one of the VANOL ligand by a molecule of substrate. The substrates are bound to the boroxinate by Hbonds to oxygen atoms O1-O3. The effects of introducing substituents at each position of the naphthalene core of the VANOL ligand are systematically investigated in an aziridination reaction. Substituents in the 4,4- and 8,8-positions have a negative effect on catalyst performance, whereas, substituents in the 7- and 7-positions have the biggest impact in a positive direction.