Study On Palladium-Catalyzed C-H Activation Reaction With Directing Group

Hydrocarbon bonds exist in almost all organic compounds.The direct selectively activation/functionalization of carbon-hydrogen bonds can provide a more direct cutting method for chemical synthesis.Therefore carbon-hydrogen bond activation has important application prospects in the field of pharmaceutical engineering.Transition metal palladium has a wide range of applications in the carbon-hydrogen bond activation reaction,and the presence of the guiding group can assist control the regioselectivity of the reaction.In this article,we mainly discuss a series of palladium-catalyzed intramolecular and intermolecular carbon-hydrogen bond activation reactions in the presence of a directing group.1.The reaction uses N,N-dimethylformamide-directed N-benzyl indole as the substrate template and palladium acetate as the catalyst.By adding silver acetate and pivalic acid,the intramolecular double-carbon-hydrogen bond activation reaction is realized.The cyclized product was obtained with the highest yield of 96%.The reaction has good tolerance to fluorine atoms,nitro groups and other groups2.The reaction uses triphenylphosphinimine with methyl sulfide in the ortho position as the template substrate,palladium acetate as the catalyst,and reacts with iodobenzene to realize the arylation reaction of the phosphinimine.After screening the reaction conditions,it was finally determined that potassium carbonate was the base,adamantanoic acid was the additive,and hexafluoroisopropanol was the solvent.Due to the instability of the raw materials under the reaction conditions,the highest yield was only 36%.3.The reaction first takes the ferrocene compound directed by picolinamide as the reaction substrate and palladium as the catalyst to carry out the arylation reaction with iodobenzene.In the end,only 8%unilateral substitution products were obtained.Based on the exploration of the first two chapters,we continue to investigate the intramolecular/intermolecular dehydrogenation coupling reaction of other indole compounds.Regrettably,the indole compounds with ferrocene did not react at all;the N-methylindole compound had an intermolecular coupling reaction with the substituted benzene solvent,and the highest yield was 40%.