Difunctionalization Of Gem-Difluoroalkenes Via Radical Process

Difluoromethylenesulfones are important biologically active compounds,and it has always been an active research field to effectively assemble difluoromethylene and sulfonyl groups into the same molecule.The synthesis of difluoromethylenesulfone compounds is mainly achieved by external difluoroalkyl reagents.Due to its special structure properties,gem-difluoroalkenes have long been considered as important fluorine-containing synthons.In the past few decades,the research on gem-difluoroalkenes has focused on:(1)nucleophilic attack and β-F elimination to generate monofluoroalkene derivatives;(2)nucleophilic addition by fluoride anions to give trifluoromethyl products.Due to the electron deficiency of the double bond in gem-difluoroalkenes,the difunctionalization of gem-difluoroalkenes has been less studied.In order to further expand the application of gem-difluoroalkenes in organic synthesis,based on the strategy of "fluorine atom economy",a new approach of photoredox-catalyzed radical addition reaction was developed to synthetically furnish difluoromethylenesulfone compounds.The main content of this thesis is described as follows:In this work,a photoredox-catalyzed bifunctionalization of aryl gem-difluoroalkenes using sulfonyl chlorides and alcohols was realized.A series ofα,α-difluoromethylene-β-alkoxysulfone compounds were synthesized.This method possesses many advantages:economical availability of start materials,mild reaction conditions and simple post-treatment.Highly functional groups compatibility was achieved,aryl sulfonyl chlorides bearing both electron-withdrawing and electron-donating groups,heteroaryl and cycloalkyl sulfonyl chlorides can be effectively tolerated.This method provides a new route for the synthesis of difluoromethylenesulfone compounds,and on the other hand,the products can be used as platform molecules for further divergent synthesis.