Synthesis Of Chiral Schiff Bases And Their Rare Earth Complexes And The Application In Asymmetric Catalyst

In this paper, five Schiff bases and their rare earth complexes were synthesized and characterized, and the application of the complexes in catalyst for hydrosis kinetic resolution (HKR) of Epichlorohydrin and asymmetric Biginelli reaction were studied.1. Synthesis and characterization of ligands and their complexes The Schiff bases and their rare earth complexes was synthesized and characterized:L~1: (+)-(R)-2,2'-bis(3,5-di-tert-butyl-2-hydroxybenzylideneamino)- 1,1'-binaphthyl;L~2: N,N'-Bis[3-methylene-(R)-1'1'-bi-2-naphthol]-3-oxa-1,5-diaminopentane;L~3: (+)-(R,R,R,R)-Diaminocyclohexane-BINOL-salen;L~4: N,N'-Bis(2-methylenepyridine)-1,2-diaminocyclohexane;L~5: (+)-(R,R,R,R)-Diamino-1,2-diphenylethane-BINOL-salen.The ligand L2 was firstly reported and ligand L4 was characterized by X-ray single crystal diffraction analysis. During the synthesis of the complexes, we chose the lanthanide picrates (Ln=La, Sm, Yb) because of their cheapness and accessibility, which is firstly reported in the asymmetric catalyst.2. Catalyst for hydrosis kinetic resolution (HKR) of EpichlorohydrinThe chiral Schiff base rare earth complexes are applied in catalyst for hydrosis kinetic resolution (HKR) of Epichlorohydrin. We developed the efficient conditions such as catalyst, time and temperature in HKR. The influence of atomic radius to catalystic activity was firstly proposed. The operation of HKR is simplified using the ligand-lanthanide picrate system and obtained the satisfying results (49% yield, 99% e.e.). At the same time, the excellent result (49% yield, >99% e.e.) was obtained by the firstly synthesized heterobimetal complex. Moreover, rare earth complexes using in HKR was firstly reported.3. Catalyst for asymmetric Biginelli reactionThe chiral Schiff bases rare earth complexes were applied in asymmetric catalyst Biginelli reaction. The excellent reaction conditions were obtained by optimizing catalysts, solvents, time and temperature. At the same time, we studied the recycling of catalyst. The excellent results were also obtained by using ligand L3 (yield 80%) in the asymmetric catalyst. Finally, substrates were expanded and excellent results were obtained. It was found that the structure of products was tricycle compounds in which the salicylaldehyde served as substrate.