Synthesis and Application of Hexamethyl-1,1′-spirobiindane-Based Phosphine-Oxazoline Ligands in Ni-Catalyzed Asymmetric Arylation of Cyclic Aldimines

With the vastly increasing applications
of chiral phosphine-oxazoline
(PHOX) hybrid ligands in various transition-metal-catalyzed reactions,
novel PHOX ligands bearing innovative backbones are highly valuable
and in great demand. This study describes the development of a new
type of chiral PHOX ligands based on a hexamethyl-1,1′-spirobiindane
scaffold and incorporating both a phosphine and an oxazoline moiety.
The optimal ligand provided high yields and excellent enantioselectivities
for the Ni-catalyzed asymmetric arylation of cyclic N-sulfonyl imines with arylboronic acids leading to chiral amines.