Cu(II) homogeneous and heterogeneous catalysts for the asymmetric Henry reaction

New Cu(II) complexes have been prepared and characterised via single crystal X-ray diffraction studies, EPR spectroscopy, elemental analysis and high resolution mass spectrometry. In all cases 1:2 (copper to ligand) stoichiometric complexes were isolated. The homogeneous Cu(II) complexes were tested for the asymmetric Henry reaction. Conversions in excess of 70% were obtained with enantioselectivities in the range 0-78%. Heterogeneous Cu(II) catalysts have been prepared. In these cases high conversions were obtained. However, after prolonged reaction time the main product observed was 1,3-dinitro-2-phenyl propane. The formation of this product can be curtailed by both decreasing the catalyst loading and employing shorter reaction times. (C) 2010 Elsevier B.V. All rights reserved.