Experimental Study For The Catalytic Synthesis Of Biaryls Compounds On The Palladium Contained Catalysts

In the presence of base (KCO) and solvent (THF, Dioxane or Toluene), 12 kinds of biphenyl compounds were synthesized by using phenylboronic acid and 12 types of substituted bromobenzenes as materials, highly effective air-stable palladium-phosphi-nous acid complex [(t-Bu)P(OH)] PdCl (abbreviated as POPd) as a catalyst, reacting for 3-6．5 hours under N. The structures of target products-biphenyl compounds were characterized through NMR, MS and IR.The effects of Pd catalysts, bases and solvents upon the cross-coupling reaction were investigated by using the reaction of phenyl boronic acid with 4-bromobenzonitrile as athe model reaction. The influences of the different substrates of bromobenzene (the electron-withdrawing groups such as-F,-COOCH,-COCH,-CN, etc., electron-releasing groups such as-OCH,-CH, etc.) upon the time and yields of Suzuki coupling reactions have been studied. We found that bromobenzene with electron-withdrawing groups can accelerate Suzuki coupling reactions through shortening the reaction time and raising the yields, bromobenzene with electron-releasing groups can hinder Suzuki coupling reactions via prolonging the reaction time and lowering the yields.The corresponding cross-coupling products were prepared through the cheaperaryl chlorides(chlorobenzene,3-chlorobenzotrifluoride) and phenylbo-ronic acid and the corresponding structures were characterized.Heterocyclic compounds are widely used in many fields,such as molecular biochemistry,organic synthesis chemisty,medical chemistry,dyestuff chemistry and grochemistry.The coupling products of 2-phenylpyridine,4-methy-2-phen-Ylpyridine were synthesized via Suzuki.Cross-coupling reaction of phynyl boronic acid,2-bromopyridine,4-methyl-2-bromopyridine and 2-fluoro-4-meh-yl-2-bromopyridine and 2-fluoro-4-methyl-5-bromopyridine as material by using the air-stable palladium(Ⅱ) complex POPd as a catalyst.The target products were identified by IR, H-NMR and MS.In the coupling reaction of phenylboronic acid and 2-bromopyridine, several factors including the species of base, solvent and catalyst, the amount of catalyst and material ratio were discussed through single-factor approach and the optimum reaction condition was obtained.