Catalytic Asymmetric Synthesis Of Rare Earth Complexes Of Chiral Amine Alcohols And Ketones

All experiments were carried out under the conditions of moisture and oxygen-free in nitrogen stream(99.99%). We prepared a kind of chiral C₂-symmetric amino alcohol L-1, L-2, L-3. They were firstly reacted with SmCl₃·4THF, GdCl₃·4THF and LaCl₃·4THF to prepare nine novel lanthanide amino alcohol complexes. The complexes have been characterized by Fourier transform infrared(IR), Ultraviolet-visible(UV-VIS), Elemental analyses, Thermal gravimetric analyses and Fluorescence measurements were also studied.The fluorescence spectra analysis showed that the amino alcohol had better fluorescence properties, but the Fluorescence properties of the amino alcohol lanthanide complexes decreased clearly. The complexes of 1, 2, 7 , 8 emitted strong green characteristic fluorescence of the ligand. But the 4, 5, 6 emitted yellow characteristic fluorescence of Sm³⁺ ions. On the basis of the comparison with the Sm³⁺ ions, the luminescent intensity of the lanthanide ion Sm³⁺ was enhanced extensively.Asymmetric transfer hydrogenation of acetophenone was conducted by using salt-free lanthanoid complexes of L-4, L-5, L-6 . The best composition of catalysis system is L-4/SmCl₃·4THF/n-KOBu^t, the best ratio of Sub./Cat./n-KOBu^t is 100:5:16, the appropriate temperature is 20℃ and reaction time is 24 hours. The best enantiosectivity(e.e.value) is 40%, and the best conversion is 97%.