Synthesis and Crystal Structure of New Chiral Ferrocenyl Schiff Base Ligands and Application in the Asymmetric Transfer Hydrogenation of Acetophenone

Novel ferrocenyl‐imine ligands 5 (5a-5c) have been synthesized for the iridium catalyzed asymmetric transfer hydrogenation of acetophenone. Ferrocenyl‐2‐thiopheneformaldehyde‐imine ligand 5c was characterized by single crystal X‐ray diffraction analysis. Single crystal X‐ray diffraction analysis reveals that the molecular structure of the title compound is enantiomerically pure and crystallizes in the noncentrosymmetric P4(1) space group, orthorhombic. The two phenyl group adopts a favored conformation perpendicularity each other. The C˭N unit is in, conjugation with the thiophene ring, as evidenced by the crystal data. The new developed ferrocenylimine and ferrocenylamine ligands(5a-5c) were applied to Ir‐catalyzed asymmetric transfer hydrogenation of acetophenone using 2‐propanol as a source of hydrogen. The results showed that the corresponding chiral alcohol could be obtained with moderate activity and excellent enantioselectivities (up to 89% ee) at desired temperature.

Keywords:

• ferrocenyl imine
• synthesis
• crystal structure
• asymmetric transfer hydrogenation
• chiral iridium complex