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Synthesis And Catalytic Properties Of Chiral Camphor Tridentate Schiff Base Ligands

Posted on:2012-12-03Degree:MasterType:Thesis
Country:ChinaCandidate:W C LiuFull Text:PDF
GTID:2191330335472062Subject:Organic Chemistry
Abstract/Summary:PDF Full Text Request
The special function of chiral compounds has been gradually realized in medical treatment, chemical, and biological and other related fields. Asymmetric synthesis method for the chiral compounds is becoming hot topic. Among these methods of asymmetric synthesis, the chiral catalyst induced asymmetric synthesis, which only needs catalytic amount of chiral compound, can produce a large amount of optically active substances. Therefore, the asymmetric catalytic synthesis method is a high efficiency procedure to prepare chiral compounds, while reducing production costs. It is also a charming point of asymmetric catalytic synthesis.The core problem of asymmetric synthesis are the chiral center's generation and control in asymmetric catalytic synthesis, the chiral centres of ligands play a key role as chiral inducing agents on the formation of optical purity products. Therefore, the synthesis of chiral ligand and study of its intermediator in the catalytic cycles become a more abstruse area. Chemists have discovered and synthesized thousands of chiral ligands and complexes with different structures, among them, tridentate Schiff base which is synthesized by chiral amino alcohol has numerous advantages and highly favored. For example, synthesis method is simple, raw materials are cheap, and they have widely practical application. In designing of chiral tridentate Schiff base ligand, the choice of chiral amino alcohols and salicylaldehyde modification is very important which often directly affect the chiral ligand recognition effect. Natural chiral compounds camphor only contain a enantiomers, using it as starting materials, we can utilize their existed chiral centers, and introduce new functional groups to the appropriate parts of the molecule to make many useful chiral ligands. Furthermore, compound derived from camphor has been widely applied in asymmetric synthesis due to their unique stereo structure and electronic effects. They have showed a good stereo induction effects in asymmetric catalysis.Based on the above research background, we synthesized two kind of chiral amino alcohol derived from natural chiral camphor. One is 3-amino-1,7,7-trimethylbicyclo[2.2.1] heptan-2-ol, which is synthesized by selectively reduction camphor quinone 3-oxime with LiAlH4. The other is 1-amino-7,7-dimethylbicyclo[2.2.1]heptan-2-ol, which is obtained by four-step reaction using camphor sulfonic acid as raw material. The two amino alcohol was used as starting material, condensed with salicylaldehyde and its derivatives, totally 15 chiral tridentate Schiff base ligand derived from natural camphor are synthesized. All compounds were characterized by IR,1H-NMR and 13C-NMR, the analysis dates of these compounds are identical with the anticipated. Based on such ligand with the unique structures and electronic effects, we have made them complex with acetic acid copper. Asymmetric Henry reaction of nitromethane and p-nitrobenzaldehyde is catalyzed by those Schiff-base complexes. We screened these complexes and discussed the relationship of catalytic performance and stereoselectivity of ligands. On this basis, the amount of catalyst, reaction temperature, solvent and other reaction conditions were optimized. Under the optimal reaction conditions, other aldehydes and nitromethane's asymmetric Henry were catalyzed by above catalyst.This thesis consists of three parts, the first chapter review the research progress of chiral ligand complexes made from tridentate Schiff base ligand and transition metal in asymmetric reactions; The second chapter report the synthesis and characterization of two chiral amino alcohol derived from camphor, derivatives of salicylaldehyde and the schiff base ligands; In the third chapter, asymmetric Henry reaction is catalyzed by complexs which synthesized by base ligand and copper acetate.
Keywords/Search Tags:Camphor, Amino alcohol, Tridentate Schiff base, Asymmetric, Henry reaction
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