Studies On Nickel-Catalyzed Michael Addition Of Benzyl Nitriles To Terminal Vinyl Ketones And Isomerization Reaction Of Allyl Alcohols

In recent years,nickel-catalyzed reactions have attracted great attention because of their high efficiency and high selectivity.Although nickel-catalyzed aryl and alkenyl C(sp2)-H activation reactions have achieved great progress,studies in nickel-catalyzed alkyl C(sp3)-H activation are quite limited.In this thesis,we mainly focused on nickel-catalyzed C-H functionalization of benzyl nitriles and nickel-catalyzed isomerization reactions of allyl alcohols.In the first part,nickel-catalyzed Michael addition of benzyl nitriles to terminal vinyl ketones was developed.The α-C-H bond functionalization of benzyl nitriles was achieved under mild conditions using Ni(cod)2 as the catalyst and 1,10-phenanthroline-type compound as the ligand.The reaction accommodated a wide range of benzyl nitriles with wide functional group tolerance.Benzyl nitriles bearing o-alkynyl,o-halogen,o-Me or α-substituent etc.underwent the desired reaction smoothly.Besides,aryl vinyl ketones bearing either electron-withdrawing or electron-donating substituents on the aryl rings converted to the corresponding products efficiently;various alkyl-substituted vinyl ketones also transformed efficiently to the corresponding products under modified reaction conditions.Mechanistic study revealed that the C-H activation step was involved in the rate-determining process.The additive of PhNHTs might act as a co-ligand.In the second part,nickel-catalyzed isomerization reaction of allyl alcohols has been established.The isomerization of alkyl-substituted allyl alcohols took place efficiently with Ni(cod)2 as the catalyst and toluene as the solvent without the need for a ligand.A wide range of alkyl allyl alcohols bearing aryl,halogen,OTB S substituent etc.at the alkyl side chain accommodated in this reaction.It’s worth noting that for the substrates bearing an ester group,the yields of the products were reduced.Isomerization reaction of aryl-substituted allyl alcohols provided carbonyl compounds also smoothly using diethyl fumarate as the additive.Diethyl fumarate may act as a weak-ligand to stabilize nickel intermediates in the reaction.