Synthesis And Catalytic Applications Of Transition Metal Catalysts

The carbon–carbon cross coupling reaction has played a key role in organicsynthesis, and has been utilized in synthetic methodologies or the targeting of naturalproducts, pharmaceuticals, and other useful materials. The Heck reaction has attractedattention ever since its discovery in the early1970s, and has provided an efficientcoupling methodology (haloarenes and olefin derivatives). The advantages of this typeof reaction are that it only requires mild reaction conditions and can tolerate a variety offunctional groups. The catalytic behavior of palladium complexes in the Heck reactionare hugely affected by the nature of the ligands employed due to electronic and stericinfluences of substituents. More recently, organophosphine ligands have been studied inorder to develop new palladium catalysts for Heck coupling. However, to overcomeissues of sensitivity and toxicity associated with organophosphines (P3+), palladiumcomplexes bearing sp3-N-bidentate chelates have been developed, which showed goodcapability in Heck coupling.In this thesis, acenaphthenequinone,2,6-dibenzhydryl-4-chlorobenzenamine,2,6-dimethylbenzenamine,2,6-diethylbenzenamine,2,6-diisopropylbenzenamine,2,4,6-trimethylbenzenamine,2,6-diethyl-4-methylbenzenamine were used as the rawmaterials. The stoichiometric condensation reaction of acenaphthenequinone and2,6-dibenzhydryl-4-chlorobenzenamine produced the2-(2,6-dibenzhydryl-4-chloropheny-limino)acenaphthylenone, which further reacted with various anilines to afford the bulkyunsymmetrical α-diimines2,6-dibenzhydryl-N-(2-aryliminoacenaphthylenylidene)-4-chl-oroaniline derivatives (L1-L5) and symmetrical α-diimine L6. All newly synthesizedα-diimines ligands (L1-L6) on reaction with PdCl2(CH3CN)2in dichloromethane formedα-diimine palladium(II) dichloride complexes (C1-C6).We analyzed the influence of the catalytic reaction conditions (temperature, solvent,base) and ligand environment to the catalytic activity. These Pd(II) complexes exhibitedhigh activities C5with conversions higher than90%) towards the Heck coupling reaction,exhibiting high thermal stability. By compared experiments, because of the effect of thesteric hindrance, we also found that the size of the hindrance group steric can affect thecatalytic activity, the small steric hindrance group’s activity is higher than the large sterichindrance group’s activity.