1067225-06-2Relevant academic research and scientific papers
Chiral phosphinoazomethinylate salts as new 'one-step available' ligands for copper-catalyzed asymmetric conjugate addition
Wencel, Joanna,Rix, Diane,Jennequin, Thomas,Labat, Stephane,Crevisy, Christophe,Mauduit, Marc
, p. 1804 - 1809 (2008/12/21)
Herein, we report the use of phosphinoazomethinylate salts as chiral efficient ligands for the copper-catalyzed asymmetric conjugate addition (ACA) of dialkylzinc to various enones. These tridentate P,N,O ligands are straightforwardly obtained in a one-step procedure from commercially available enantiopure α-aminoacids. Performing the conjugate addition in the greener AcOEt solvent, high enantioselectivities were reached for both cyclic and acyclic enones ranging between 72% to 98% ee and 96% to >99%, respectively. The 2/1 Cu/ligand ratio required to obtain high enantioselectivities, led us to envisage a copper-copper bi-metallic catalytic system for this transformation.
