Nickel-catalyzed Reductive Cross-Coupling Of Aryl Halides And Nickel-catalyzed Allylation Reaction Of Aldehydes And Ketones

Transiion-metal-catalyzed direct reductive coupling of two electrophilic reagents is ahighly efficient strategy for the generation of carbon-carbon bonds in organicchemistry. The first section of this thesis describes a noval synthetic strategy ofunsymmetrical biaryl compounds via direct nickel-catalyzed reductive coupling oftwo aryl halides. Although numerous methods have been developed in the synthesisof aryl-aryl bonds, the coupling of two electron-rich aryl halides has not been reported.In this thesis, we report the cross coupling of two electron-rich aryl halides. Thesecond section describes the nickel-catalyzed allylation reaction of aldehydes andketones. This is the first time that such type of reactions are catalyzed by nickelinstead of Pd or Ir. The distinctive feautures of these methods are highlighted asfollows.1) The reaction conditions using NiI₂and4,4’-dimethyl bipyridine in the presence ofreducing agent zinc powder provide unsymmetric biaryl compounds via thecoupling of two aryl halides. The mild reaction conditions are carried out at roomtemperature, under which a wide range of functional groups could be used.2) We have developed nickel-catalyzed reductive allylation of aldehydes and ketonesfrom the reactions of allylic acetates and carbonyl compounds. This methoddemonstrates high efficency under mild reaction conditions, provding thehomoallylic ketones in high yields. The enantioselectivity of the products was alsostudied in which moderate ees have been obtained.