Study On The Formation Of C–O And C–S Bonds Catalyzed By Cationic Lanthanide Complexes

The formation of carbon-oxygen bond and carbon-sulfur bond catalyzed by cationic lanthanide complexes[Ln?CH₃CN?₉]³⁺[?AlCl₄?₃]^3–·?CH₃CN?was studied in this thesis.The results provide good examples of using cationic lanthanide complexes[Ln?CH₃CN?₉]³⁺[?AlCl₄?₃]^3–·CH₃CN,which are highly electrophilic and easily available,as efficient catalysts in organic synthesis.The thesis is composed of two parts as follows:1.Cationic lanthanide complexes[Ln?CH₃CN?₉]³⁺[?AlCl₄?₃]^3–·?CH₃CN?served as efficient catalysts for the tandem Friedel–Crafts alkylation/ketalization reaction of2-hydroxychalcones with naphthols/substituted phenols.A series of diaryl-fused2,8-dioxabicyclo[3.3.1]nonanes were obtained in moderate to high yields.The reaction is stereoselective and can be performed without a Br?nsted acid or a noble metal.The high catalytic efficiency of the cationic lanthanide complex[Yb?CH₃CN?₉]³⁺[?AlCl₄?₃]^3–·?CH₃CN?compared with that of YbCl₃ can be attributed to the increased Lewis acidity of the Yb species as a result of cation formation.2.Cationic aluminum complex[Al Cl?CH₃CN?₅]²⁺[?AlCl₄?₂]^2–·?CH₃CN?served as efficient catalyst for the tandem Friedel–Crafts alkylation/ketalization reaction of2-hydroxychalconeswithnaphthols.Aseriesofdiaryl-fused2,8-dioxabicyclo[3.3.1]nonanes were obtained,but the yields are not as good as those obtained with cationic lanthanide complexes.3.The hydrothiolation of olefins with thiophenols or thiols was efficiently catalyzed by cationic lanthanide complexes[Ln?CH₃CN?₉]³⁺[?AlCl₄?₃]^3–·?CH₃CN?.A series of thio ethers were selectively formed as Markovnikov regioselection products inmoderatetohighyieldsinthepresenceof0.5mol%of[Yb?CH₃CN?₉]³⁺[?AlCl₄?₃]^3–·CH₃CN under solvent-free conditions.