Application Of Ionic Liquids In C-C/C-N Bond Coupling And Dehydration Of Fructose

Ionic liquids(ILs) constitute an attractive alternative for a number of organic transformations due to their unique properties and the advantages of catalyst recycling, improved selectivity, and ease in product isolation. ILs have also been employed as solvents for transition-metal-catalyzed C-H activation reactions and conversion of biomass. To the best of our knowledge, up to now, there are no examples on the study of the C-H bond activation using classical heterocyclic ionic liquids as catalysts. In recent years, as an emerging field in C-H activations, cross-dehydrogenative coupling(CDC) represented a valuable and atom-efficient coupling strategy for the construction C-C bond and C-X(X = N, O, S).The first chapter mainly introduced the studies on the ILs employed as solvents for transition-metal-catalyzed C-H activation reactions in recent years and conversion of biomass. Next, summarized the cross-dehydrogenative coupling reactions of aldehydes. Furthermore, the sp3C-H bond activation reactions of benzylic compounds and other compounds have also been introduced.In the second chapter, we presented metal-free efficient synthesis of 11H-benzothieno[3,2-b]chromen-11-ones via a intramolecular CDC reaction of 3-aryloxybenzo[b]thiophene-2-carbaldehydes utilizing easily recycled and reused ionic liquid [Bmim]Br as promoter in aqueous media. The promoter can be easily recycled and reused with the same efficacies for at least five cycles.In the third chapter, we developed here an efficient and green method for the synthesis of N-alkylated azoles, with IL 1-butylpyridinium iodide([Bpy]I) as the catalyst and TBHP being the oxidant. It is the first example of the heterocyclic IL-catalyzed sp3C-H bond activation coupling of benzylic compounds and azoles. IL can be recycled and reused with the similar efficacies for at least eight cycles.In the fourth chapter, the design and synthesis of four SO3H-functionalized benzotriazole ionic liquids and catalyst for dehydration of fructose into 5-HMF. The results showed that 1-ethyl-3-(4-sulfobutyl)-1H-benzo[d][1,2,3]triazol-3-ium chloride IL2 had a better catalytic performance. The yield reached 91.1% under the optimum reaction conditions: fructose 1.0 g, catalyst IL2 0.5 g, H2 O 1.0 m L, MIBK 9.0 m L, reaction temperature 120 oC and reaction time 2 h. Catslyst recycled and reused with the same efficacies for at least five cycles.