Study On Base-mediated Syntheses Of Diarylketones With Molecular Oxygen Participation

Diarylketones,in general,serve as structural units in numerous pharmaceuticals,naturally-occurring products,and organic functional materials.Also,they are widely used as important intermediates in the construction of all kinds of C-based chemical bonds or heterocycles.Traditionally,the synthetic methods of arylketones include classical Friedel-Crafts acylation of arenes,oxidation of secondary alcohols,CO insertion reactions and transition metal-catalyzed coupling reactions.The study on synthesis of diarylketones has been well developed with the advancement of C-H activation strategies.However,toxic or expensive metal catalysts,harmful chemical oxidants and harsh reaction conditions are still involved in most of the transformations.Therefore,exploring a non-metallic,non-chemical oxidant involved in the green conversion method has important academic and social values.In this thesis,the autoxidation strategy of C-H bond was used to explore the new methods for the base-mediated aerobic synthesis of diaryl ketones.The main contents are as follows:Firstly,a series of diarylmethane derivatives were synthesized by the Friedel-Crafts reaction of benzyl alcohols/benzyl chlorides with aromatic hydrocarbons using ether solution of boron trifluoride as the alkylating agent.Secondly,the synthesis of diarylmethanone from diarylmethane was studied systematically.The reaction conditions were optimized by the autoxidative carbonylation of diphenylmethane as a model,the optimum reaction conditions were determined as follows:dry DMSO being the solvent,sodium tert-butoxide being the base to promote the reaction with oxygen balloon,the molar ratio of diphenylmethane to sodium tert-butoxide being 1:2,stirring at 50? for half an hour,the reaction yield was 92%.And 22 kinds of diarylmethanone compounds were synthesized efficiently,indicating that the method has a good functional group tolerance and selectivity.Finally,we studied the synthesis of nitro group-containing diarylmethanones by cross-coupling of arylacetic acid esters and nitroaromatics.The reaction conditions were optimized by the cross coupling of methyl phenylacetate and nitrobenzene as the model.The optimum conditions for obtaining diarylketones were determined as follows:In the open-to-air condition,dry DMSO was used as the solvent,and methyl phenylacetate/nitrobenzene/sodium tert-butoxide = 1/2/2(mol)was used as the material ratio,and the yield of 4-nitrobenzophenone was 80%.The results showed that the reaction had good applicability to the aromatic acetate,but the nitrobenzene analog was limited.In conclusion,this paper has established a new method for the synthesis of diarylketones without metal catalysis,no chemical oxidant,cheap raw material and simple operation.In particular,the cascade cross-coupling/oxidative decarboxylation reaction of the acetoacetate with nitrobenzenes is well complemental to the current preparative methods of nitro-substituted arylketones.