Study On The Coupling Reactions Of α,β-Unsaturated Alkenes Or Arylsilanes And Boron-promoted Ether Interchange Reactions

In this thesis,coupling reactions ofα,β-unsaturated alkenes or arylsilanes were investigated.In addition,boron-promoted ether interchange reactions were explored.The results are as follows:1.Palladium-catalyzed reductive Heck reactions of（hetero）cycloalkyl iodides andα,β-unsaturated alkenes.The palladium catalyzed reductive Heck reactions of（hetero）cycloalkyl iodides withα,β-unsaturated alkenes were developed.Using（hetero）cycloalkyl iodides as substrates,1.5 equiv ofα,β-unsaturated alkenes as coupling reagents,10 mol%Pd（OAc）₂ as catalyst,20 mol%Dppf（1,1’-Bis（diphenylphosphino）ferrocene）as ligand,2.0 equiv Et₃N as base and hydride source in Ph CF₃ under an argon atmosphere at 130 ^oC for 12 h（Scheme 1）,a variety of substituted（hetero）cycloalkanes were achieved in reasonable yields.In addition,the hydride source was afforded by Et₃N and no other reductant or base was needed.The reaction system broadens the C（sp³）-hybridized electrophiles of palladium-catalyzed intermolecular reductive Heck reaction and provides a new method for the synthesis of potentially bioactive（hetero）cycloalkane derivatives.2.Palladium-catalyzed Hiyama cross-couplings of 3-iodoazetidine and arylsilanes.An efficient approach for the synthesis of 3-arylazetidines via the palladium-catalyzed Hiyama cross-couplings of 3-iodoazetidine and arylsilanes had been developed.The reactions were carried out under the optimal condition with3-iodoazetidine as substrate,2.0 equiv of arylsilanes as coupling reagents,5 mol%Pd（OAc）₂ as catalyst,10 mol%Dppf（1,1’-Bis（diphenylphosphino）ferrocene）as ligand,2.0 equiv TBAF（tetrabutylammonium fluoride）as base and dioxane as solvent under an argon atmosphere at 60 ^oC for 12 hours.A variety of3-arylazetidines were obtained in moderate to good yields（30%-88%）with reasonable regioselectivity（Scheme 2）.The reaction system has the advantages of simple operation,mild conditions,and good functional group tolerance.The method provides a convenient way to synthesize 3-arylazetidines.3.Transition metal-free cross-couplings of arylsilanes with diethylaminosulfur trifluoride（DAST）reagent.The efficient method for transition metal-free cross-couplings of arylsilanes with diethylaminosulfur trifluoride（DAST）reagent was developed.Using arylsilanes as substrates,4.0 equiv of Na HCO₃ as base and DCM as solvent under an argon atmosphere at room temperature for 1 h,a series of aromatic sulfinamide compounds were obtained（Scheme 3）.Notable advantages of this approch included simple operation,transition metal-free and mild reaction conditions.The reaction system provides a simple and practical method for the synthesis of aromatic sulfinamide compounds.4.Synthesis of alkyl nitroaromatic ethers via boron-promoted ether interchange reactions.A protocol for boron-promoted ether interchange reactions of methoxynitroarenes was developed.With nitroaromatic methyl ethers as substrates,under condition A:5.0 equiv of KO^tBu as base,alcohols as solvents and reactants in the presence of 2.0 equiv 1,1-diboromethane at 90 ^oC for 12 h under argon atmosphere or condition B:5.0 equiv of KO^tBu as base and V_alcohols/V_xylene=3:2 as solvents in the presence of 4.0 equiv Ph Bpin at 80 ^oC for 12 h under argon atmosphere,a series of ether exchange products were obtained in moderate to good yields（Scheme 4）.The method constitutes an operationally simple and scalable strategy for the synthesis of alkyl nitroaromatic ethers.