Research On The Synthesis Of Chalcone And Benzimidazole Derivatives Based On Aromatic Aldehydes

Chalcone and its derivatives,as a kind of important natural products,are not only found in various plants but also an important part of drug active molecules.In addition,nitrogen-containing heterocyclic compounds are also an important class of natural products,and benzimidazole,as a very important class of heterocyclic compounds,is also one of the core structural frameworks of bioactive molecules and pharmaceuticals.After summarizing the literature,the system for preparing chalcone compounds was determined: graphene-supported zinc oxide(ZnO/RGO)catalyst,a heterogeneous supported catalyst,was prepared from graphene and zinc acetate dihydrate by hydrothermal method and characterized.It was then used to catalyze the Claisen-Schmidt condensation reaction,the optimum conditions were determined by screening the solvent,temperature,time and amount of the catalyst,and 23 chalcone compounds were obtained.The activity of the catalyst is good after four cycles.It is proved by the hot filtration experiment and ICP-MS test that it is the catalyst rather than the particles leaching out of the catalyst in the reaction solution that really plays a catalytic role.Next,determining the photocatalytic preparation of 2-arylbenzimidazoles conditions: o-phenylenediamine and benzaldehyde were used as the substrate,and the optimum conditions was determined that the substituted o-phenylenediamine(0.1 mmol)and the aromatic aldehyde(0.1 mmol)as the substrates are dissolved in 2 mL of acetonitrile,and 2 mol% of fluorescein is used as a catalyst.The reaction was carried out in the air under 10 W Blue LED for 2 hours.The suitability of the reaction was investigated by using a substrate with a substituent and 18 2-arylbenzimidazoles were obtained and characterized.The mechanism was explored and confirmed by experiments to further understand this reaction.It is important that the system is relatively mild and avoids additional oxidants or metals.This is the first example of the preparation of 2-arylbenzimidazole using fluorescein as a photocatalyst.