Study On Transition Metal-Catalyzed Arylation Reaction Of Benzothiazoles With Diaryliodonium Salts

The study on the arylation reaction of benzothiazoles with diaryliodonium salts as arylating reagents is described in this thesis.It includes the following three chapters:Chapter 1:Review of arylation reactions involving diaryliodonium salts as arylating reagentsIn recent years,diaryliodonium?III?salts?Ar₂IX?have received increasing attention from scientists and research groups around the world as versatile arylating reagents because of their favorable safety profile,ease of handling,and air and moisture stability.As hypervalent iodine reagents,diaryliodonium salts have a highly electron-deficient n-ature and excellent leaving-group ability.In the past few years,diaryliodonium salts a-s arylating reagents have been successfully used in the transition-metal-catalyzed cross-coupling C-H and N-H arylation reactions of heteroaromatic compounds to form the c-orresponding arylation products under mild conditions.In this chapter,a review of the progress in the preparation of diaryliodonium salts and the applications in organic synthesis is described in detail.These substrates involved in this reaction catalyzed bytransition metals have included substrates such as 1,2,3-benzotriazoles,pyridines,quinolines,oxazolidinones,amides,indoles,and coumarins.Direct arylations of arenes,N-heteroarenes,and 1-acetyl-indolin-3-ones with diaryliodonium salts have also been efficiently conducted without the use of a transition-metal catalyst.Chapter 2:Palladium-catalyzed C2-arylation of benzothiazoles with diaryliodo nium saltsA novel,simple and direct arylation of benzothiazoles with diaryliodonium salts to form2-arylbenzothiazoles is developed.This cross-coupling reaction is catalyzed by palladium bromide in the presence of cesium carbonate and phosphorus ligand.The effects of various reaction conditions,such as various catalysts,solvents,ligands,bases and different diaryliodonium anions,on the reaction were investigated in detail.The optimum reaction conditions were determined.The results show that the protocol has a wide substrate scope and well group tolerance to give 21 desired products in moderate to high yields?52%-85%?.The probable reaction mechanism is proposed.Chapter 3:Copper-catalyzed C2-arylation of benzothiazoles with diaryliodonium saltsIn this chapter,we continue to study copper-catalyzed arylation reaction of benzothiazoles to form 2-arylbenzothiazoles.The optimized results indicate that cuprous iodide is the optimum catalyst in the presence of cesium carbonate as a base and2,2'-bipyridine as a ligand.The method also has a wide substrate range and functional group tolerance,the product yield of up to 90%.The product products were thoroughly characterized by IR,¹H NMR,¹³C NMR,and MS and so on,under the optimum conditions.