Preparation And Application Of Fluorous Organocatalysts

Recently, organocatalysts have advantages like low toxicity, operational simplicity and efficiency over inorganic or metal-based catalysts and attract much interest. However, their major limitation for catalysis is the difficulty of recovering the catalysts. An alternative strategy is to design efficient, recyclable and subsequently reusable versions of organocatalysts, fluorous reusable organocatalysts are important branches of those.This thesis focuses on the design, synthesis and the application of fluorous organocatalysts. There are two main parts in the study, the design and application of traditional organocatalysts with fluorous tags and the the design and application of new type of fluorous organocatalysts. In the catalyst recycling experiments, we applied the Fluorous solid phase extraction (F-SPE) and fluorous precipitation technology.The fluorous hydrazine-1,2-bis(carbothioate) was synthesized with2-perfluorohexyl ethanol and1,10-(thio)carbonyl diimidazole as starting material. Together with (N-Chlorosuccinimide) NCS, this fluorous compound could catalyze the synthesis of polysubstituted1,2-dihydroquinolines, and the critical intermediate of this reaction was imine or enamine complex; this catalytic system could also promote the acetalization of aldehydes, related study showed the hydrogen bond played an important role in this catalytic reaction.Fluorous4-N,N-dimethylaminopyridium iodide could be easily prepared with fluorous iodide and DMAP as starting matiral, this fluorous organocatalyst could efficiently catalyze acylation reaction of alcohol. The acylation reactions proceeded somoothly and the fluorous catalyst could be easily recovered by precipitation in hexane.We also synthesized the flourous1,4-disubstituted [1,2,3]-triazole, this fluorous compound could more efficiently catalyze the adol condensation; this was also an excellent ligand for the palladium catalyzed Suzuki-Miyaura and Mizoroki-Heck reaction. This fluorous compound could be easily recovered and there was no significant loss in the catalytic activity after recovering.In the last part, we designed and synthesized the flourous ethylenediamine, the preliminary study showed the flourous compound can promote the direct C-H arylation of unactivated arenes. Based on the study of flourous ethylenediamine, we found di-tert-butyl peroxide could efficiently promote the coupling of aryl halides with benzene derivatives through a chain homolytic aromatic substitution (HAS) mechanism in the presence of potassium tert-butoxide.