The Synthesis And Application Of Air-stable And Water-tolerant Alkylcyclopentadienyl Zirconium Perfluorooctane Sulfonate Complexs

Organometallic Lewis acid catalysts were widely applied in organic synthesis. But most of them suffered from one or more disadvantages such as air- or moisture-sensitive; the poor catalytic efficiency and selectivity; the toxicity and unbenign to the environment; expensive and so on, which limited their application. Therefore, it was highly desirable to develop some novel Lewis acid catalysts with the highly efficient, well stable, green and general property.Recently, zirconium complexes had aroused much interest. For example, Cp2 Zr Cl2 and Cp2Zr（OTf）₂ were applied in various reactions, such as olefin polymerization and the C-C bond forming reactions. However, the weak acidity of Cp2 Zr Cl2, the unstability and the feasible hydrolysis of Cp2Zr（OTf）₂ greatly limited their application.To overcome these shortcomings, a series of air-stable and water-tolerant metallocene complexes（Cp2M（OSO2C8F17）₂, M= Ti, Zr, Hf） were synthesized in our group by construction of stable C-M bond and incorporation of perfluoroalkyl（aryl）sulfonate moieties（a strongly withdrawing-electron group）. However, their relative low solubility in organic solvents declined the catalytic efficiency possibly due to the strong lipophobic nature of C8F17 group. Therefore, we wished to incorporate an alkyl group into the cyclopentadienyl ring in order to increase the solubility of catalysts in organic solvents as well as the catalytic efficiency. Some innovative results and conclusion were listed as follows:（1） A novel air-stable Lewis acidic complex of [{CH3Cp Zr（OH₂）3}2（μ2-OH）₂][OSO2C8F17]4·2H₂O·1THF·2（C₃H₆O）（2a·2H₂O·THF·2（C₃H₆O）） was successfully synthesized and its structure was determined to be binuclear by single-crystal X-ray. The complex was characterized by various techniques such as TG-DSC analysis, conductivity measurement and acid strength（H0）. The results demonstrated that the novel complex had good thermal-stability（being active below 200 oC）, good solubility in organic solvents and strong acidity. The complex could be used as an excellent catalyst for the Friedel-Crafts acylation and the Mannich reactions with good yield and reusability.（2） A novel air-stable Lewis acidic complex of [{CH3CH2Cp Zr（OH₂）3}2（μ2-OH）₂][OSO2C8F17]4·4H₂O·2THF（3a·4H₂O·2THF） was synthesized and its structure was determined to be binuclear by single-crystal X-ray. The complex demonstrated strong acidity and good thermally-stability（being active below 250 oC） by various techniques such as TG-DSC analysis, conductivity measurement and acid strength（H0）. It can dissolve well in the organic solvents. The complex could be used as an excellent catalyst for the three-component reactions of indoles with benzaldehydes and N,N-dimethylanilines in more than 60 % yields.（3） A novel air-stable Lewis acidic complex of（[（i-Pr Cp）₂Zr（H₂O）3]（OSO2C8F17）₂·H₂O·3THF）（4a·H₂O·3THF） was successfully synthesized and its structure was determined to be uninuclear by X-ray. The complex was also characterized with other techniques such as TG-DSC analysis, conductivity measurement and acid strength（H0）. It can be used as a highly efficient catalyst for the direct alkylation of 1,3-dicarbonyl derivatives with benzhydrylic alcohols in more than 85 % yields. The novel complex had the advantages of water tolerance, air-stability, thermally-stability, highly catalytic efficiency, good solubility in organic solvents and reusability.（4） Three novel air-stable Lewis acidic complexes of [Cp Zr（OH₂）3]2（m2-OH）₂（OSO2C8F17）4·2THF·4H₂O（5a·4H₂O·2THF）, [n-Bu Cp Zr（OH₂）3]2（m2-OH）₂（OSO2C8F17）4·6H₂O（6a·6H₂O） and [t-Bu Cp Zr（OH₂）3]2（m2-OH）₂（OSO2C8F17）4·2C₃H₆O·8H₂O（7a·8H₂O·2（C₃H₆O）） had been synthesized and their structures were determined to be binuclear by single-crystal X-ray. The structure of 5a·4H₂O·2THF was different from the reported uninuclear Cp2Zr（OSO2C8F17）4, even though they were obtained according to the same reactors and the identical synthetic procedures. All the three complexes were characterized by various techniques such as TG-DSC analysis, conductivity measurement and acid strength（H0）. It was found that these novel complexs also had the advantages of good stability, strong acidity and good solubility in organic solvents.[Cp Zr（OH₂）3]2（m2-OH）₂（OSO2C8F17）4·2THF·4H₂O（5a·4H₂O·2THF） was investigated to catalyze the classical Mannich reaction, giving the targeted products in the similar yields with its counterpart uninuclear Cp2Zr（OSO2C8F17）₂.[n-Bu Cp Zr（OH₂）3]2（m2-OH）₂（OSO2C8F17）4·6H₂O（6a·6H₂O） was used to catalyze the amidation reaction of secondary benzylic with carboxamides, giving their corresponding products in more than 70 % yields.[t-Bu Cp Zr（OH₂）3]2（m2-OH）₂（OSO2C8F17）4·2C₃H₆O·8H₂O（7a·8H₂O·2（C₃H₆O）） was investigated to catalyze the Michael reaction of indoles with enone, giving the indole derivatives in high yields（more than 80 %）.To test the reusability of these catalysts and the reproducibility of catalytic performance, the there complexes were exemplified to be subjected to cycles of Friedel-Crafts acylation of anisole. The results showed that the catalysts could be recycled at least five times without obvious influence on reaction yields, demonstrating that the catalysts were stable and suitable for reuse.