Study On The Synthesis Of 1-Indenone And 2H-Indazole Derivatives Via Radical Reaction

Indenones are important structural skeletons,which widely existing in drugs and natural products.The construction and structural modification of the indenones have been one of the important research directions of medicinal chemists and organic chemists.At present,the methods for the construction of functionalized indenones include the intramolecular Friedel-Crafts acylation,Heck-Larock cyclylation,and the catalytic reactions of precious metals such as Rh and Pd.However,these methods have some shortcomings,such as harsh reaction conditions and poor regioselectivity.On the other hand,2H-indazoles have effective biological activities,such as antitumor and antibacterial.Herein,the preparation of functionalized 2H-indazoles by simple and efficient methods are of great research significance.In recent years,radical chemistry has developed into a powerful and versatile tool for organic synthesis.Particularly,radical reactions have become one of the important research direction because of their wide application in the construction of complicated carbocyclic or heterocyclic framework of organic and pharmaceutical molecules.Based on the relevant literatures,a new method for the synthesis of 1-indanone derivatives by radical cascade reaction and the preparation of 2H-indazole derivatives by radical reaction was studied in this paper by using silver salt as catalyst and persulfate as oxidant.The main research works are as follows:(1)A method was developed to prepare 1,3-dicarbonyl 1-indenone derivatives by one-pot using silver nitrate as catalyst,potassium persulfate as the oxidant,1,3-diarylpropynones and 1,3-dicarbonyl compounds as substrates.A total of 22 indenones were prepared.Mechanism study showed that the reaction was radical mechanism,and two new C-C bonds were constructed by addition/cyclization reaction.This method is characterized by simple operation,high atomic economy and high yield.(2)A method was developed to prepare 1,3-dicarbonyl 2H-indazole derivatives using silver nitrate as catalyst,potassium persulfate as oxidant,2-phenyl-2H-indazoles and 1,3-dicarbonyl compounds as substrates.A total of 6 functionalized 2H-indazoles were prepared.Mechanism study showed that the reaction was radical mechanism.The applicability and application of this method needs further study.The research in this paper provides a new strategy for the synthesis of functionalized indenones and 2H-indazoles.The synthesized dicaronyl 1-indenones and 2H-indazoles are both new compounds,which greatly expand the functionalized 1-indenones and 2H-indazoles compound library.