Benzaldehyde has been trimethylsilylcyanated with a catalyst prepared in situ from titanium tetraisopropoxide and chiral Schiff bases. Cyanohydrin is obtalned in moderate e.e.values
We have prepared supramolecular systems of chiral Schiff base Ni(II), Cu(II), Zn(II) complexes and colloidal gold nanoparticles (AuNP) of 10 nm diameters. They demonstrated that direct adsorption of chiral Schiff base...We have prepared supramolecular systems of chiral Schiff base Ni(II), Cu(II), Zn(II) complexes and colloidal gold nanoparticles (AuNP) of 10 nm diameters. They demonstrated that direct adsorption of chiral Schiff base metal complex on the surface of AuNP owing to observation of clear induced CD spectra for the first time. We observed and discussed induced CD bands on AuNP from chiral Schiff base Ni(II), Cu(II), Zn(II) complexes.展开更多
An array of C2-symmetric chiral Schiff bases of substituted salicylaldehyde （1R, 2R）-1, 2-cyclohexanediamine and （R）-（＋）-2, 2＇-diamino-1, 1＇-binaphthalene, incorporated with lanthanide complexes, have been ap...An array of C2-symmetric chiral Schiff bases of substituted salicylaldehyde （1R, 2R）-1, 2-cyclohexanediamine and （R）-（＋）-2, 2＇-diamino-1, 1＇-binaphthalene, incorporated with lanthanide complexes, have been applied as catalysts for asymmetric hydrogenation of acetophenone for the first time. Highly enantioselective product with 90% enantiomeric excess （e.e.） was obtained when the catalyst, hybridized by the bulky electron-donating 3, 5-di-tert-butyl substituted Schiff base （2） and SmCl3.4THF, was employed.展开更多
Enantiomeric four chelated planar square schiff base Cu 2+ and Ni 2+ complexes were synthesized using ( 1R,trans ) and ( 1S,trans) N,N bis(2 hydroxyphenyl methylene) 1,2 diaminocyclohexane. Th...Enantiomeric four chelated planar square schiff base Cu 2+ and Ni 2+ complexes were synthesized using ( 1R,trans ) and ( 1S,trans) N,N bis(2 hydroxyphenyl methylene) 1,2 diaminocyclohexane. The chirality could not be shown by usual UV Vis spectra. The intrinsic chiral difference of the enantiomeric complexes can be displayed by circular dichroism(CD) spectra. The Cotton effect of every polarlight sensitive absorption of one enantiomer will be the opposite of that of the other enantiomer. It was found that no tetrahedron form exists for Ni 2+ complexes, which was determined with UV Vis spectra and Electron Paramagnetic Resonance(EPR) measures.展开更多
Twelve chiral copper(Ⅱ) Schiff base complexes, derived from (R) (+) 2 amino 1,1 diaryl 1 propanol with substituted salicylaldehydes, were examined as a catalyst for asymmetric cyclopropanation of styrene with ethyl d...Twelve chiral copper(Ⅱ) Schiff base complexes, derived from (R) (+) 2 amino 1,1 diaryl 1 propanol with substituted salicylaldehydes, were examined as a catalyst for asymmetric cyclopropanation of styrene with ethyl diazoacetate. It was found that the substituents at 3 and 5 positions of salicylaldehyde in the ligands had great effects on catalytic activity and enantioselectivity of the catalyst. The complex with strong electron withdrawing group (NO 2) at 5 position and the smallest stereo hinder (H) at 3 position of salicylaldehyde showed highly catalytic activity and enantioselectivity, up to ee =87 4% for trans and ee =82 8% for cis isomers respectively, and the ratio 39/61 of cis to trans isomers was obtained at 40 ℃ with 1,2 dichloroethane as solvent.展开更多
A novel chiral Salen ligand with a glucose moiety was synthesized from the condensation of 1,2:5,6-di-O-isopropylidene-3-O-methylene-5-(3-tert-butyl-2-hydroxy benzaldehyde) -α-D-glucofuranose with (1R,2R)-1,2-diamino...A novel chiral Salen ligand with a glucose moiety was synthesized from the condensation of 1,2:5,6-di-O-isopropylidene-3-O-methylene-5-(3-tert-butyl-2-hydroxy benzaldehyde) -α-D-glucofuranose with (1R,2R)-1,2-diaminocyclohexane. Several chiral complexes of Mn3+, Fe3+, Co2+ and Cu2+ were prepared from this ligand. Both the ligand and the complexes were characterized by elemental analysis, NMR, IR, MS, and UV-Vis.展开更多
文摘Benzaldehyde has been trimethylsilylcyanated with a catalyst prepared in situ from titanium tetraisopropoxide and chiral Schiff bases. Cyanohydrin is obtalned in moderate e.e.values
文摘We have prepared supramolecular systems of chiral Schiff base Ni(II), Cu(II), Zn(II) complexes and colloidal gold nanoparticles (AuNP) of 10 nm diameters. They demonstrated that direct adsorption of chiral Schiff base metal complex on the surface of AuNP owing to observation of clear induced CD spectra for the first time. We observed and discussed induced CD bands on AuNP from chiral Schiff base Ni(II), Cu(II), Zn(II) complexes.
基金This work is financially supported by the National Natural Science Foundation of China （No. 20271018 ＆ 20572018） Heilongjiang Province （ZJG0504, 1055HZ001 ＆ GB04A416）Heilongjiang University.
文摘An array of C2-symmetric chiral Schiff bases of substituted salicylaldehyde （1R, 2R）-1, 2-cyclohexanediamine and （R）-（＋）-2, 2＇-diamino-1, 1＇-binaphthalene, incorporated with lanthanide complexes, have been applied as catalysts for asymmetric hydrogenation of acetophenone for the first time. Highly enantioselective product with 90% enantiomeric excess （e.e.） was obtained when the catalyst, hybridized by the bulky electron-donating 3, 5-di-tert-butyl substituted Schiff base （2） and SmCl3.4THF, was employed.
文摘Enantiomeric four chelated planar square schiff base Cu 2+ and Ni 2+ complexes were synthesized using ( 1R,trans ) and ( 1S,trans) N,N bis(2 hydroxyphenyl methylene) 1,2 diaminocyclohexane. The chirality could not be shown by usual UV Vis spectra. The intrinsic chiral difference of the enantiomeric complexes can be displayed by circular dichroism(CD) spectra. The Cotton effect of every polarlight sensitive absorption of one enantiomer will be the opposite of that of the other enantiomer. It was found that no tetrahedron form exists for Ni 2+ complexes, which was determined with UV Vis spectra and Electron Paramagnetic Resonance(EPR) measures.
文摘Twelve chiral copper(Ⅱ) Schiff base complexes, derived from (R) (+) 2 amino 1,1 diaryl 1 propanol with substituted salicylaldehydes, were examined as a catalyst for asymmetric cyclopropanation of styrene with ethyl diazoacetate. It was found that the substituents at 3 and 5 positions of salicylaldehyde in the ligands had great effects on catalytic activity and enantioselectivity of the catalyst. The complex with strong electron withdrawing group (NO 2) at 5 position and the smallest stereo hinder (H) at 3 position of salicylaldehyde showed highly catalytic activity and enantioselectivity, up to ee =87 4% for trans and ee =82 8% for cis isomers respectively, and the ratio 39/61 of cis to trans isomers was obtained at 40 ℃ with 1,2 dichloroethane as solvent.
文摘A novel chiral Salen ligand with a glucose moiety was synthesized from the condensation of 1,2:5,6-di-O-isopropylidene-3-O-methylene-5-(3-tert-butyl-2-hydroxy benzaldehyde) -α-D-glucofuranose with (1R,2R)-1,2-diaminocyclohexane. Several chiral complexes of Mn3+, Fe3+, Co2+ and Cu2+ were prepared from this ligand. Both the ligand and the complexes were characterized by elemental analysis, NMR, IR, MS, and UV-Vis.
