《Tetrahedron, Asymmetry: The International Journal for Repid Publication on all Aspects of Asymmetry in Orgainc, Inorganic, Organometallic, Physical and Bio-Organic Chemistry》 2008年19卷15期
摘要
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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 straightforwa...
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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 alpha-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. (C) 2008 Elsevier Ltd. All rights reserved.
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