Copper(II) complexes containing chiral substituted 2-(4-isopropyl-4-methyl-4,5-dihydro-1H-imidazol-5-one-2-yl)pyridine ligands: Synthesis, X-ray structural studies and asymmetric catalysis

New chiral N,N-bidentate ligands derived from substituted 2-(4-isopropyl-4-methyl-4,5-dihydro-1H-imidazol-5-one-2-yl)pyridines have been prepared and characterised by means of 1H, 13C NMR spectroscopy and optical rotation. Their Cu(II) complexes were characterized by means of elemental analysis, 1H NMR spectroscopy and MS. By means of X-ray diffraction, molecular geometry of the complex of 2-(1-methyl-4-isopropyl-4-methyl-4,5-dihydro-1H-imidazol-5-one-2-yl)pyridine with copper(II) chloride was determined. The complex exhibits heterochiral dimeric arrangement of two square pyramids with one terminal and one bridge-forming chlorine atoms and two nitrogen atoms in the bases of the pyramids. The tops of these pyramids are formed by the remaining chlorine atoms. The complexes prepared catalyse the Henry reaction with the overall yields of 41–97% and with the maximum enantioselective excess of 19%.

Graphical abstractNew chiral N,N-bidentate ligands derived from substituted 2-(4-isopropyl-4-methyl-4,5-dihydro-1H-imidazol-5-on-2-yl)pyridines have been prepared and characterised by means of 1H, 13C NMR spectroscopy and optical rotation. Their Cu(II) complexes were characterised by means of elemental analysis, 1H NMR spectroscopy and MS. By means of X-ray diffraction, molecular geometry of the complex of 2-(1-methyl-4-isopropyl-4-methyl-4,5-dihydro-1H-imidazol-5-one-2-yl)pyridine with copper(II) chloride was determined.Figure optionsDownload full-size imageDownload as PowerPoint slide