Ligand-Free Cross-Coupling Reaction

Transition metal-catalyzed cross-coupling reactions are the important methods for the selective construction of the carbon-carbon bonds.A number of transion-metal catalysts and new ligands have been found recently to improve these reactions.This dissertation mainly described two ligand-free cross-coupling protocols,including ligand-free palladium-catalyzed Suzuki cross-coupling reaction and copper-catalyzed Sonogashira cross-coupling reaction.Copper-catalyzed oxidation of benzyl alcohols has also been developed.1.The Pd(OAc)₂/MeONa/EtOH catalytic system have been found to catalyze the Suzuki cross-coupling reaction effectively.In the presence of 1 mol%of Pd(OAc)₂,a variety of aryl halides reacted with arylboronic acids rapidly in good to excellent yields at room temperature. Moreover,the system could also be applied in the reaction of heteroaryl halides with arylboronic acids.2.Et₃N was found to be an efficient solvent to improve the Sonogashira crossing-coupling reaction catalyzed by Cu(OAc)₂.In the presence of Cu(OAc)₂ and Et₃N,a variety of aryl halides were coupled with terminal alkynes to afford the corresponding desired products in moderate to excellent yields.3.An efficient catalytic system for the oxidant of benzyl alcohols has been developed.In the present of Cu₂O nanoparticles and 1,10-phenanthroline,benzyl alcohols could be oxidated to afford the corresponding aldehydes or ketones in moderate to good yield under mild condition.