Study On The Synthesis Of 2-Functionalized Benzothiazole/Selenazole Derivatives Through Tandem Reaction Of Isonitriles

Functionalized benzothiazoles are frequently presented in natural products,drugs and biologically active synthetic compounds.2-Halogenated benzothiazoles are the common intermediates for the synthesis of their 2-functionalized derivatives through transition metal-catalyzed cross-coupling reactions or aromatic nucleophilic substitution reactions.So far,although many synthetic methods of 2-halobenzothiazoles have been successively reported,from the point of view of synthetic methods,these methods are limited to using preformed benzothiazoles as starting materials.Therefore,it is still of great significance to develop new synthetic methods for the construction of 2-halogenated benzothiazoles.In addition,the 2-aminobenzothiazole derivatives also have good biological and pharmaceutical activities.Recently,the radical cyclization of thio-functionalized arylisocyanides became a useful tool for the preparation 2-alkyl/fluoroalkyl/aryl benzothiazoles.In this thesis,we explored the ionic cascade insertion/cyclization of thia/selenide functionalized arylisocyanides for the efficient and practical synthesis of 2-halogenated benzothiazole/benzoselenazole derivatives.Meanwhile,2-aminobenzothiazoles can also be easily prepared by a one-pot cascade reaction of 2-isocyanoaryl sulfide,iodine and amine.This thesis is mainly divided into four chapters:Chapter 1:Research background and topic selectionThis section mainly summarizes the synthetic methods of 2-halogenated and 2-amino benzothiazoles.The structure and properties of isonitrile,the main types of reactions that it participates in,and the reactions involving 2-isocyanophenylmethyl sulfide/selenoether are also introduced.Finally,the topic selection of this thesis is proposed.Chapter 2 and Chapter 3:Synthesis of 2-halogenated benzothio/selenazole and 2-amino benzothia/selenazole.This part contains the development of ionic cascade insertion/cyclization of thia/selenide functionalized arylisocyanides for the efficient and practical synthesis of 2-halogenated benzothiazole/benzoselenazole derivatives under catalyst-free conditions.2-aminobenzothiazoles are also easily prepared by a one-pot cascade reaction of 2-isocyanoaryl sulfide,iodine and amine.It mainly includes the screening of reaction conditions,exploration of scope of the substrate,and proposing the possible mechanism.Chapter 4:Experimental partThis section contains the synthesis of raw materials,the experimental process for the synthesis of 2-functionalized benzothio/selenazole and the characterization data of the product.