The Design And Synthesis Of Perfluoroaryl Hypervalent Iodine Reagent And Its Reaction With Terminal Alkynes

Organic fluorine compounds have unique application value in the fields of medicine,agricultural chemicals,science and so on.The introduction of fluorine greatly reduces the HUMO-LIMO levels,which is especially evident in polyfluoroaryl compounds.However,these compounds are often synthesized by toxic tin reagents or dangerous lithium reagents,leading to the great limitation of their applicabilities.Therefore,how to sythesize organic fluorine compounds have increasingly attached great importance of scientists.With the con-tinuous development of hypervalent iodine chemistry,the role of hypervalent iodine reagents in synthesisy has become increasingly prominent because they are lower toxic,environmen-tally friendly,readily accessible,and so on.Therefore,they could participate in many reac-tions as an oxidant or transfer reagents.We designed and synthesized a class of perfluoroaryl hypervalent iodine reagents as sources of polyfluoroarylated compounds and applied them to the perfluoroarylation of ter-minal alkynes.The main contents are as follows:1. Firstly,chloroiodane was synthesized by the chlorination of 2-iodobenzoic acid with TCICA,and 2-?2-iodophenyl?propan-2-ol produced by methyl-2-iodobenzoate was bromin-ated with NBS to synthesize bromoiodane.Then,the resulted chloro/bromoiodane was re-acted with C₆F₅Mg Br in Et₂O and has been left in an ice-salt bath?-15??for 24 h.0.1 m L water was added to the reaction mixture during the halfway and the reaction continued.The non-cyclic products were formed at the beginning of the reaction and increasing temperature had no significant effect on the reaction.Combining the Grignard reagent's activity,the final reaction temperature was determined to be-20°C.After 24 h,12 h,6 h,and 3 h,the reaction results did not change significantly.Given the demand for mass production,the reaction time was finally determined to be 6 h.The isolated product was found to be an open-looped io-donium salt in the form of HBr.Based on iodonium salt,KHCO₃ was used to remove HBr to obtain pentafluorophenyl and nonafluorobiphenyl hypervalent iodine prducts,among which nonafluorobiphenyl hypervalent iodine compounds can be prepared in large quantities.Con-trolling the amount of Grignard reagent can respectively gain the corresponding products.Finally,a feasible reaction mechanism is proposed in combination with related literatures,which might undergo a concerted,free radical pathway,and involve an addition-elimination mechanism.Different from the typical Grignard reaction,the reaction occurs at the site of iodine instead of carbon,related with perfluoroaryl groups,so this reaction was called“non-classical”Grignard reaction.2. The above nonafluorobiphenyl hypervalent iodine reagent was applied to the per-fluoroarylation of terminal alkynes using phenylacetylene as a substrate. The optimal condi-tions were released according to a series of experiments.Under the protection of argon,the reaction was performed with 10 mol%Cu I and 1,10-phen as the catalyst and ligand,1.2 equiv of KHCO₃ as the base,and DCM as the solvent,which has been lasted for 12 h at room temperature.With the optimized conditions in hand,the universality of substrates was inves-tigated to obtain different perfluoroarylated phenylacetylene compounds at moderate yield which were able to be further derivated to make contributions to the field of fluorine chem-istry and materials'science.At last,a feasible reaction mechanism was proposed by referring to related literature:Hypervalent iodine-mediated pathway and copper-catalyzed pathway.Based on the activity of nonafluorobiphenyl hypervalent iodine reagent,the hypervalent io-dine-mediated pathway could be progressed on the center of iodine.And the copper catalyed pathway was complied with the general law of transition metal catalysis,producing highly active trivalent copper species,which became the feature of the pathway.