Study On The Gem-Difluoroalkenes Reaction Of Boronic Acids With TFHZ-Tfs

Gem-difluoroalkenes structure is a ubiquitous structural unit in fluorinated compounds and is widely present in bioactive molecules,drugs,pesticides and organic materials.At the same time,gem-difluoroalkenes are also an important intermediate for organic synthesis.Therefore the development of a synthetic gem-difluoroalkenes molecular structure strategy has always been an active research area,which has attracted widespread attention from chemists.Currently,strategies including direct difluoroalkenylation from difluorocarbene precursors and carbonyl compounds,?-elimination strategies for functionalized difluoromethyl compounds,defluoroalkylation of?-trifluoromethyl olefins and derivatization of difluorovinyl compounds.Among these methods,the synthesis of difluoroolefins using diazo compounds as raw materials is a research topic that has attracted much attention in recent years.Trifluoromethyldiazomethane is a very common structural unit in organic synthesis.It is used in the construction of various organic conversion reactions containing trifluoromethyl compounds.As a highly active synthon,it is a potential pyrene difluoroethylene functionalized structural units have received increasing attention in recent years.However,examples of the conversion of diazo compounds into gem-difluoroalkenes are scarce,and there is only one method for rapidly generating gem-difluoroalkenes from trifluoromethyldiazomethane.Meanwhile,the studies on fluorene difluoroolefins have shown that alkyl-substituted gem-difluoroalkenes compounds are more biologically active than aryl gem-difluoroalkenes.The synthesis of alkyl gem-difluoroalkenes has been a difficult problem in organic fluorine chemistry.In this paper,we use a non-toxic and stable trifluoroacetaldehyde N-triftosylhydrazone?TFHZ-Tfs?as a substitute for CF₃CHN₂.This compound can be coupled with organoboric acid to form gem-difluoroalkenes.This reaction avoids the direct use of toxic and explosive trifluoromethyldiazomethane,and obtains a series of gem-difluoroalkenes compounds without using a transition metal catalyst.More importantly,this reaction is very effective and the highest yield of the product is 94%.It has a wide range of substrate,including alkyl,alkenyl and arylboronic acids.The reaction was carried out under base condition to avoid the influence of traditional acidic conditions.