Study On The Cycloaddition Reaction Of Difluorocarbene With Polyene

Fluorochemicals show extensive applications in biological materials,pharmaceu-ticals,pesticides and aviation industries due to their special physical,chemical and biological activities.How to introduce fluorine-containing groups into organic compounds or construct universal fluorine-containing blocks and intermediates economically and efficiently has attracted wide attention.Meanwhile,difluorocarbene intermediates is a effective method to introduce difluoromethylene into organic molecules.At present,the cycloaddition reactions involving difluorocarbene are widely,but few are reported to cycloaddit with polyenes to construct difluoride fused-ring compounds.Therefore,It is valueable to develop cycloaddition reaction of difluorocarbene and polyene.This article elaborates on two parts of the research including[8+1]cycloaddition reaction with difluorocarbene and azaheptafulvenes as well as[4+1]cycloaddition reaction with difluorocarbene and ortho-Quinone methide?o-QM?.In this study,the[8+1]cycloaddition of Ph₃P⁺CF₂COO^-and azaheptafulvenes was successfully achieved for the first time.This cycloaddition reaction can be carried out efficiently,without catalyst,in a tetrahydrofuran solvent at room temperature for 4hours or at 50 ^oC for 1 hour.Through this gentle method,we obtained 20 series of 7,4-fused difluoromedium-cyclic compounds with a reaction yield of up to 99%.It was confirmed that the reaction has good compatibility with both electron-donating and electron-withdrawing group,and It can also have a medium yield when the benzene ring is connected to the active molecule.Besides,excellent yield can also be obtained when the reaction was scaled up,indicating that the reaction has the prospect of application in some extent.In addition to the above[8+1]cycloaddition,we have also successfully achieved[4+1]cycloaddition reaction with TMSCF₂Br,as the difluorocarbene source,and o-QM.Without any metal catalyst,under the initiation of 20 mmol%TBAB,the reaction was heated in a toluene solvent at 80 ^oC for 12 hours,and a benzofluorene difluorofuran compound could be obtained in a yield of 76%.Through substrate expansion,we found that no other precursor pathway can react,but only this intermediate has the reaction effect.The research in this project is mainly devoted to the development of a method for cycloaddition of polyenes using difluorocarbene.20 kinds of difluoro 7,4-fused ring compounds were constructed by[8+1]higher-order cycloaddition with Ph₃P⁺CF₂COO^-and azaheptafulvenes.Meanwhile,benzofluorene difluorofuran compound was constructed with o-QM and TMSCF₂Br via[4+1]cycloaddition.