Study On The Construction Of Geminal Difluoromethylene Compounds Based On The Transformation Reaction Of Geminal Difluoroolefin

Fluorinated compounds are a unique structural motif with important applications in the fields of drug discovery,agrochemical,and material science.It is of great significance to develop synthetic methods for difluoromethyl compounds.In this thesis,we mainly study the construction of various substituted gem-difluoromethylene-containing compounds from gem-difluoroalkenes.The main contents are as follows:The first chapter mainly discussed the applications of fluorinated compounds in fields of biomedicine,agricultural and material science.Also,traditional synthetic methods for gem-difluoromethylene-containing compounds and their limitations were introduced.Additionally,recent advance in[3,3]-σrearrangement reaction involving N-allyl hydrazone and dihalogenation functionalization of olefins were introduced.In the second chapter,controlled synthesis ofα-CF₂H orα-CF₂Cl styrenes from the same precursors:dehydazinative hydrogenation or chlorination of 3,3-difluoroallyl hydrazines has been studied.We have screened metal salts,solvents and additives with 3,3-difluoroallyl hydrazine as the model substrate.After obtaining the optimal reaction conditions,we have examined the substrate scope and obtained a series of target products with medium to good yields.Subsequently,gram scale experiment and derivative application of the product have been carried out.Finally,the possible reaction mechanism has been proposed based on the controlled experiments.In the third chapter,we mainly studied the construction of gem-difluoroallyl containing compounds based on[3,3]-σrearrangement reaction of gem-difluoro-N-allyl hydrazones.We have explored the effects of acids,oxidants,and substituents on the substrate of gem-difluoro-N-allyl hydrazones to screened the conditions to obtain the target compound.This method broadens the substrate range of[3,3]-σrearrangement of N-allyl hydrazone.In the fourth chapter,we mainly studied the construction of ortho-chlorinated CF₂Cl-containing compounds by dihalogenation functionalization of gem-difluoroalkenes.We have explored the dihalogenated functionalization of gem-difluoroalkenes under the catalysis of copper chloride,and obtained 4-（1,2-dichloro-2,2-difluoroethyl）-1,1’-biphenyl in good yields.