Design and synthesis of air-stable, storable chiral phosphoramidite ligands for transition-metal-catalyzed enantioselective reactions

Abstract

The synthesis of a new family of phosphoramidite ligands is described through a straightforward two-step process. Selective reduction of cyclohexane dinitriles afforded novel amines, which were subsequently reacted with BINOL-chlorophosphites to yield the corresponding phosphoramidites. Remarkably, these ligands exhibited exceptional stability against air, moisture, and in solution, as confirmed by ³¹P NMR spectroscopy. The performance of these ligands was assessed in two benchmark asymmetric reactions—the rhodium-catalyzed arylation of aldehydes and the copper-catalyzed conjugate addition of diethyl zinc to chalcones—demonstrating notable influence of the ligand structure.