Synthesis of Electronically Deficient Atropisomeric Bisphosphine Ligands and Their Application in Asymmetric Hydrogenation of Quinolines

A series of electronically deficient atropisomeric bisphosphine ligands have been synthesized from (S)-MeO-BiPhep. The introduction of electron-withdrawing groups in the ligands had a dramatic influence on both the enantioselectivity and the activity of catalyst. The iridium complex of the MeO-BiPhep-based ligand bearing a trifluoromethanesulfonyl group was successfully applied in the asymmetric hydrogenation of quinolines with ee values of up to 95% and turnover numbers (TON) of up to 14,600.