Studies On The Transition-Metal-Catalyzed Ring-Opening And Rearrangement Reactions Of Benzo[d]Isoxazoles

Imine structural motifs are widely found in pharmaceuticals,advanced materials,and in the synthesis of natural product-like molecules.Due to the electrophilic nature of the C=N double bond,imines can undergo highly selective addition reactions with nucleophiles,thus enabling the resulting products to achieve extra applications in pesticides,medicines,materials,and the related areas.In addition,imine molecules are also widely used in the field of molecular recognition and catalysis.Conventionally,the method of synthesizing imines react with aldehydes(ketones)and primary amines in the presence of dehydrating agents.In this paper,we mainly study the efficient and practical construction of aromatic heterocyclic imine derivatives,through the ring-opening reaction of benzoxazole.This article is divided into four parts:In the first part: A brief summary of various methods for the synthesis of imines were reviewed.Methods such as cross-coupling of alcohols and amines,oxidative coupling of amine-amines,and oxidation of secondary amines were summarized.Besides,the dearomatization protocols and the reactions of alkynes with amines to synthesize imines were also presented.The catalytic reactions in these methods were classified into transition-metal catalysis,metals-free reactions,photo-catalysis,and heterogeneous catalysis.In the second part: A rhodium-catalyzed synthesis of 3-spiroindolyl-2-imine compounds with 3-diazoindolin-2-imine and benzo[d]isoxazole was developed.The [5+1]-cycloaddition and rearrangement reaction of Rh-carbene intermediate with benzo[d]isoxazole was proposed in this reaction.This procedure was convenient to operate,and the product can be obtained in a moderate to good yield.The structure of the expected product was verified via X-ray diffraction analysis.In the third part: multi-component reactions of copper-catalyzed benzo[d]isoxazoles with terminal alkynes and sulfonyl azides were reported,which produces imine products in good to excellent yields and excellent chemoselectivity.The reaction is resistant to a wide variety of functional groups and only releases nitrogen as the sole by-product.The sulfonimide group can be removed to give a biologically active 4-amino-2H-chromenone in high yield.The fourth part is the experimental section of this thesis,which including all characterization data of all new compounds.