| The osmium-catalyzed asymmetric dihydroxylation (AD) of olefins provides one of the most effective methods for the preparation of vicinal diols. Almost all kinds of olefmic substrates can be transformed to the corresponding diols by means of AD reaction. The chiral osmium catalyst is generated in situ by the chiral ligand complexing with Os04 in the reaction. Although AD reaction can be widely applied to the synthesis of Pharmaceuticals, natural products and fine chemicals, the high cost of osmium and chiral ligands as well as the high toxicity and volatility of the osmium component has restricted its use in industry. So exploration of the repetitive use of the chiral osmium catalyst for AD reaction is urgent. The present research work focuses on two aspects. On one hand, the most successful alkaloid-derived ligands have been attached to a soluble or insoluble support covalently, but additional OsO4 is necessary to maintain the consistent catalytic activity during the reuse of supported chiral ligand in the next AD reaction. On the other hand, immobilization of osmium tetroxide based on microencapsulation, ion-exchange techniques, and osmylation of resins has made it possible to recover and reuse of the osmium, but failed to recover thechiral ligand at the same time. At present, simultaneous recovery and reuse of the chiral ligand and OsO4 are of major interest. Very recently, an ionic liquid and (ethylene glycol) (PEG, FW 400) have been employed as reaction media as well as immobilizing agents for the catalyst in AD reaction. However, the high molar ratio of the OsO4/ligand/substrate (0.01/0.05/1) and obvious leaching of both catalytic components made these attempts ineffective.The research work of this thesis focuses on the development of the recoverable and reusable chiral catalysts and catalytic system in the AD reaction of olefins. It mainly includes following aspects:1. Three chiral mono-quaterized bis-cinchona alkaloid ligands 8, 9, 10 were designed and synthesized.Treatment of 1,4-dichlorophthalazine with quinine or quinidine provided (QN)2PHAL and (QD)2PHAL. (QN)2PHAL, (DHQ)2PHAL and (QD)2PHAL were quaternized by refluxing with benzyl bromide to give ligands 8, 9 and 10 respectively.2. The chiral ligands were applied to the AD reaction of olefins with NMO as co-oxidant and PEG (400 MW) or [bmimjPFs as reaction media. When the reaction was finished, the product diol could be extracted by tert-butyl methyl ether, while most of the alkaloid ligand and osmium tetroxide were remained in the reaction media due to the low solubility of the ligand in ether and special encapsulating effect of ionic liquid and PEG on osmium tetroxide. The recovered ionic liquid or PEG phase containing ligand and OsO4 could be recycled five times without any addition of OsO4 and ligand. The results of AD reactions are as follows:(1) When the AD reaction of eight olefins was performed at 0.5mol% Os04 and 2mol% ligand 8 in PEG/ NMO system, the diols were obtained in 78-90% yields and 78-96% ees (except for frww-5-decene and ally naphthyl ether). We also found that low temperature (0 C) was benefit to increasing entioselectivity. In the recycling experiments of AD reaction, with trans-stilbene being substrate, chiral ligand 8 and OsO4 could be recoveredand reused for five times with high catalytic activity and stereoselectivity.(2) The ligand 9 is different from ligand 8 in that the substitute group at the 3-position of quinuclidine is ethyl group, so it won't be oxidized in the AD reaction. 9 was applied to the AD reaction of eight olefins in PEG/ NMO system according to the protocol of ligand 8. The yields and ees of the diols were 70-90% and 77~96%( except for trans-5-decenc and ally naphthyl ether) respectively. With trans-stilbene as the substrate, chiral ligand and OsO4 could be recovered and reused five times in the AD reaction with high catalytic activity and stereoselectivity.(3) ligand 10 and 8 are pseudo-enantiomers, and the AD reactions using ligand 8 and 10 delivered chiral diols of opposite configurat...
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