Synthesis of tunable bisphosphine ligands and their application in asymmetric hydrogenation of quinolines

A series of tunable axial chiral bisphosphine ligands have been synthesized from (S)-MeO-Biphep. The Ir complex of the MeO-PEG-supported ligand (S)-4k has been successfully applied in asymmetric hydrogenation of quinolines with up to 92% ee. The catalyst system is air-stable and recyclable.