Study On The Ring-opening Functionalization And Thiofunctionalization Reactions Of Benzo N-heterocycles

Benzo N-heterocyclic structures are widely found in pharmaceuticals,agricultural chemicals,and functional material molecules,and have attracted attention due to their unique biological and pharmacological activities.Considering the importance of benzo aza-aromatics,the studies which focus on the synthesis and transformation of benzo Nheterocycles will greatly enrich these compounds library and promote the development of medicine,materials and other fields.At present,the conversion of benzo Nheterocycles mainly focuses on ring-opening reactions and direct functionalization.Among them,the ring-opening reactions of benzo N-heterocycles is used to synthesize new nitrogen-containing aromatic compounds;The direct functionalization is generally used to realize the modification of benzo N-heterocycles.Benzothiazole and indole are two general benzo N-heterocycles structural units.It is important to develop new strategies to realize the transformation and modification of benzothiazole and indole.In this thesis,based on the summary of recent research progress in the ring-opening reaction of benzothiazoles and the synthesis of arylthioindoles by C2/C3 thiofunctionalization of indoles,we realized the copper-catalyzed the ring-opening of reaction of benzothiazoles to synthesize aryl(2-iminoaryl)thioethers,and the reaction of indoles with p-toluenesulfonyl cyanide to synthesize C2/C3-arylthioindoles in the absence of metal.This thesis included the following four parts:Chapter ⅠThe ring-opening reaction of benzothiazoles and the synthesis of C2/C3-arylthioindoles under metal-free conditions were systematically summarized.Chapter ⅡA copper-catalyzed three components ring-opening of benzothiazoles with aryl iodides and O-benzoyl hydroxylamines have been explored.The aryl(2-iminoaryl)thioethers were synthesized through the construction of C-S and C-N bonds.The reaction displayed good substrate applicability and functional groups tolerance.The reaction substrate can be extended to benzoxazoles.The mechanism studies have demonstrated that the secondary amine was the possible intermediate,and the deuteration experiments have indicated that the C-H bond dehydroisomerization of benzothiazoles was not involved in the reaction.Chapter ⅢThe copper-catalyzed ring-opening S-arylation and N-iminylation of benzothiazoles with aryl iodides and formamides to synthesize aryl(2-iminoaryl)thioethers have been studied using formamides as the solvents and nitrogen sources.The mechanism studies have demonstrated that 2-isocyanobenzene sulfur anions were produced by the ring-opening reaction of benzothiazoles with the help of copper catalyst and base.Copper catalyzed the cross-coupling reaction between aryl iodides and 2-isocyanobenzene sulfur anions to synthesize diaryl thioethers.Subsequently,the amines generated from decarbonylation of formamides underwent nucleophilic attack on the isocyano groups of diaryl thioethers to obtain the aryl(2-iminoaryl)thioethers.Chapter ⅣUsing p-Toluenesulfonyl cyanide(Ts CN)as the sulfur sources,the direct C-H thiofunctionalization of indoles to construct C-S bonds without metal catalyst have been studied,and controllable chemoselectivity and regioselectivity synthesis of 3-arylsulfinylated,3-arylsulfenylated and 2-arylsulfonylated indoles were realized.The process had broad substrate scopes,in addition to indoles,pyrroles and 10 Hphenothiazine can also participate in the sulfidation reaction to obtain corresponding thio-functionalized products.