Synthesis Of Benzo Nitrogen-Containing Heterocyclic Compounds By Isatin-involved Tandem Reaction

Nitrogen-containing heterocyclic compounds are widely found in natural products and drug molecules,and play an important role in the fields of biomedicine,pesticides and materials.As a kind of cheap compounds with rich reaction sites and wide sources,isatin has become a key building unit for constructing C-N bonds and synthesizing nitrogen-containing heterocycles in organic reactions.The lactam and dicarbonyl structure of isatin can show both nucleophilicity and electrophilicity.This structure with multiple reactivity has broad development space in the construction of aromatic heterocyclic skeleton.Therefore,the development of simple and efficient reactions based on isatin as a substrate to construct diverse compounds has attracted extensive attention from chemists.In this thesis,the synthetic methods of isatin-involved acridone derivatives and isatin-involved benzimidazolo[1,2-c]quinazolin-6-one derivatives were studied,mainly including the following three chapters.:In the first part,starting from the reactions involving isatin,benzyne and Mo（CO）₆,the development history and common reactions of the reactions in recent decades are briefly described,and the research topic of this thesis is proposed.The second part mainly introduces a green and effective method for the synthesis of acridone and its derivatives:the molecular skeleton of acridone compounds was effectively constructed by the reaction of isatin and benzyne without transition metal catalyst.In the condition screening stage,it was found that the oxygen in the air can be used as an oxidant to participate in the reaction in the Baeyer-Villiger oxidation ring expansion step.Through further screening of the reaction conditions,the reaction can be carried out by air or tert-butyl perbenzoate（TBPB）oxidation system.The method is simple,has good functional group compatibility,and can obtain a series of acridone compounds in good yield.The third part mainly introduces a new method to construct the structure of benzimidazolo[1,2-c]quinazolin-6-one:starting from isatin and o-nitroaniline,one-pot synthesis of benzimidazolo[1,2-c]quinazolin-6-one and its derivatives was realized by Mo（CO）₆ catalysis.The reaction has mild conditions,simple operation and wide functional group compatibility.A series of benzimidazolo[1,2-c]quinazolin-6-ones can be obtained in excellent yields,showing good substrate universality.Among them,Mo（CO）₆not only acts as a reducing agent for nitro,but also plays a role in promoting cyclization.It has good atomic economy and provides a new scheme for the construction of such compounds.