Synthesis and application of a new hexamethyl-1,1'-spirobiindane-based chiral bisphosphine (HMSI-PHOS) ligand in asymmetric allylic alkylation.

The emerging and versatile application of chiral bisphosphine ligands in diverse asymmetric reactions has resulted in great demand for novel bisphosphine ligands containing different innovative backbones. Herein, a new type of chiral spiro bisphosphine ligand (HMSI-PHOS) has been developed on the basis of a hexamethyl-1,1'-spirobiindane motif. A series of new HMSI-PHOS ligands were synthesized and used in Pd-catalyzed asymmetric allylic alkylation reactions, and moderate to good yields and enantioselectivities were obtained with phenyl substituted ligands.