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Keywords:

  • copper;
  • enantioselectivity;
  • homogeneous catalysis;
  • ligand design;
  • ligand effects

Abstract

Multitopic chiral copper complexes based on bis(oxazoline) have been applied in the enantioselective α-hydrazination of β-ketoesters. High yields and excellent enantioselectivities were obtained. Furthermore, the catalytic systems have been recovered in up to ten cycles without loss of activity or enantioselectivity. The formation of coordination polymers [polytopic ligand–Cu]n has been confirmed by UV/Vis titrations. Significant metal leaching was observed on increasing the topicity of the ligand. The nature of the catalyst was studied by nonlinear effect experiments.