Pd/Al?OH?₃-Catalyzed Suzuki-Miyaura Cross-coupling Of Arenediazonium Tetrafluoroborate Salts

The Suzuki-Miyaura cross-coupling reaction of organoboron compounds and organic halides or pseudohalides can be considered as one of the most efficient methods for the construction of carbon-carbon bonds.It has gained prominence in recent years at an industrial level,mainly in the synthesis of pharmaceuticals and fine chemicals.In conclusion,Suzuki-Miyaura coupling reaction of the research is the focus and hotspot in the research of the chemical workers at home and abroad.It was reported that in this paper the Suzuki-Miyaura cross-coupling reactions of arenediazonium tetrafluoroborate salts with potassium phenyltrifluoroborate were catalyzed by Kwon's reported palladium nanoparticles.The extending reactions gave good yields and more importantly,the catalyst was highly active,a novel and moisture-stable,which was successfully applied on couplings of arylboronic acids with aryl halides and arenediazonium tetrafluoroborate salts by our group.And then,this nanopalladium catalyst was reported for the first time to show excellent catalytic effection in the Suzuki cross-coupling reactions of arenediazonium tetrafluoroborate salts with potassium phenyltriflioroborate.The reaction conditions were optimized focused on the Pd/Al?OH?₃ loading,solvent,solvent dose and temperature were screened.After all these extensive experiments it was discovered that when reactions were performed on a 0.2 mmol scale of benzenediazonium tetrafluoroborate,the optimal conditions employed 0.1 mol%Pd and 1.1 equiv.of potassium 4-bromophenyl trifluoroborate in 1.0 mL MeOH for 6 h at 25? which provided biphenyl in 93%isolated yield.Next,a variety of arenediazonium tetrafluoroborate salts and potassium phenyltrifluoroborate were examined for the cross-coupling reactions using optimized conditions.This method has good universality.It was shown that the electronic nature of diazonium salts and the steric nature of potassium phenyltrifluoroborate produced good to excellent yields of coupling products.The product yield is between 8-97%.Through the substrate extension has received 21 compounds,the products were eamained by TLC,IR,1HNMR.The advantages of this method included:?1?easily available,high activity?2?under non-degassed and non-anhydrous condition,with easy operation;?3?mild reaction conditions,less side effects.Therefore,this research provides a reference value for our future research.