Fluoroalkylation Of Unsaturated C-c Bonds Using Phenol As Catalyst

In recent years,fluoroalkylation involving visible light promoted reaction based on the electron donor-acceptor complex has drawed intense interest.This strategs is very promising because no catalyst is needed.However,some drawbacks still exist in those reaction systems,it suitable for special compounds and excess amount of electron donor atom is still required for such transformations.Based on this situation,we propose using the cheap and widely available electron-donor compound phenol as catalyst promoted fluoroalkylation of unsaturated compounds.Then,we reason that allylphenol could be fluoroalkylated smoothly without adding any other phenols as catalysts.Finally,We further propose a mechanism involving an electron donor–acceptor?EDA?complexObjective:In view of the demand of green chemistry,simple,efficient and high atom economy protocol,it is hoped that fluoroalkylation can be efficiently realized by using cheap electron donor compounds as catalyst based on the EDA complexes mechanism.Methods:First,we conducted difluoroalkylation reaction by treating allylbenzene and ethyl iododifluoroacetate as model substrates.An evaluation of difffferent inexpensive electron donor compounds revealed that 2-bromophenol was the optimal choice.Then the different bases,solvents and wavelengths of blue LEDs were investigated,and finally a phenol catalyst system was established.With the optimized reaction conditions in hand,the scope of this photochemical atom transfer radical addition was next evaluated using abundant and structurally diverse terminal alkenes and alkynes.To our delight,a Heck-type reaction occurred when allylbenzene was treated with ethyl iododifluoroacetate with K₂CO₃ was used as a base and DMSO solvent.Interestingly,the reaction can also proceed smoothly without addition of any other phenols as catalysts when using allylphenols as substrates,perfluoroalkyl iodides and ethyl iododifluoroacetate as fluoroalkyl sources.Finally,cyclization products could be selectively obtained in moderate to good yields in the presence of K₂CO₃ and THF when ethyl iododifluoroacetate was treated with 2-allylphenol.Results:We report a new protocol for the fluoroalkylation of alkenes and alkynes by using 2-bromophenol as a catalyst.This reaction can be tailored for different reaction modes by altering the base and solvent,which feature a wide substrate scope and excellent functional group tolerance with high chemo-and regioselectivities.We further propose a mechanism involving an electron donor–acceptor?EDA?complex.Conclusion:Catalytic amount of electron donor compound has been developed fluoroalkylation reaction effectively.