Synthesis Of Polyfluoroaryl Hypervalent Iodine Reagents And Their Reaction With Alkynes

For many aromatic systems,the introduction of fluorine-containing segments effectively improves their performance as liquid crystal materials.The development of these materials and the development of organofluorides containing polyfluoroaryl moieties are linked,so the development of related polyfluoroarylation reagents and the preparation of fluorides containing polyfluorophenyl moieties in this linkage is extremely important.However,the structures of the products that can be synthesized by the existing reactions are relatively limited,which will limit the application of these compounds.Therefore,we hope to develop a class of reagents with low toxicity,environmental friendliness and better reactivity and use them for the synthesis of various types of polyfluoroaryl compounds.In this thesis,a series of novel polyfluoroaryl hypervalent iodine reagents were prepared by reacting bromine-containing hypervalent iodine reagents with newly prepared RMgBr mainly by"non-classical"Grignard method,and the reaction of these reagents with acetylene derivatives was explored,The main contents are as follows:1.Synthesis of a series of polyfluoroaryl hypervalent iodine reagents.In this part of the work,we first used two methods to synthesize the desired polyfluorobromobenzene:（1）using Pd（OAc）₂,AgNO₃ as catalyst,K₂CO₃ as base,phenol or its derivatives and bromine Pentafluorobenzene reaction.（2）The intermediate product is obtained by reacting benzyl alcohol or its derivative with dimethyl carbonate,and then the intermediate product,potassium tert-butoxide and bromopentafluorobenzene are reacted to obtain the product.Next,the corresponding Grignard reagent RMgBr was synthesized from polyfluorobromobenzene and magnesium turnings in THF.Then the obtained Grignard reagents were reacted with bromine hypervalent iodine reagents to synthesize a series of polyfluoroaryl hypervalent iodine reagents.Changing the experimental temperature can effectively improve the yield of the reaction.2.The reaction of polyfluoroaryl hypervalent iodine reagents with p-methoxyphenylacetylene was explored.In this part of the work,using CuI as catalyst,1,10-phenanthroline as ligand,and excess potassium bicarbonate as base,various polyfluoroaryl hypervalent iodine reagents were combined with p-methoxyphenylacetylene in dichloromethane.The reaction was carried out in methane for 12 h to obtain nine polyfluorophenylalkyne compounds.3.The reaction of hypervalent iodine reagents containing benzyloxytetrafluoro moieties with p-methoxyphenylacetylene was explored.In this part of the work,benzyloxytetrafluorohydric iodine reagent was reacted with 4-methoxyphenylacetylene to explore the general adaptation of the substrate.Under the optimization,the optimal reaction4.Conditions were determined as follows:under the condition of Ar,CuI and Pd[P（C₆H₅）₃]₄ were used as catalysts,bis（2-pyridyl）ketone and KHCO₃ were used as ligand and base,and DCM was used.The desired product was obtained by reacting at 30 ℃ for 12 h.After exploring the universality of the substrates,it was found that most of the products could be obtained in good yields.More than twenty acetylenes containing benzyloxytetrafluoro fragments were synthesized.5.The reaction mechanism of hypervalent iodine reagent containing benzyloxytetrafluoro moiety with 4-methoxyphenylacetylene was explored.A possible mechanism was proposed through a series of experiments.