Synthesis And Arylation Of 2-mercapto Benzopentazole Compounds

Sulfur-containing benzene fused heterocyclic compounds have a wide application in pharmaceutical,pesticide,material science,biochemistry and other fields.In particular,sulfur-containing benzopentazoles have received much attention from many chemists and pharmacists due to their unique pharmacological activities and biological activities.In this thesis,general methods were developed for the synthesis of2-mercaptobenzothiazoles,2-mercaptobenzoxazoles,benzimidazole-2-thiones,2-S-arylbenzothiazoles,2-S-arylbenzoxazoles,2-S-arylbenzimidazoles and1-N-aryl-2-S-arylbenzimidazoles using sodium dimethyldithiocarbamate or tetramethylthiuram disulfide as sulfuration agents.This thesis mainly includes the following five parts:1.Briefly introduction about the application and methods for synthesis of2-mercaptobenzothiazoles,2-mercaptobenzoxazoles,benzimidazole-2-thiones,2-S-arylbenzothiazoles,2-S-arylbenzoxazoles,2-S-arylbenzimidazoles.2.A high-efficiency synthetic method for the Al Cl₃-mediated preparation of2-mercaptobenzopentazoles?2-mercaptobenzothiazoles,2-mercaptobenzoxazoles,benzimidazole-2-thiones?is described using sodium dimethyldithiocarbamate as sulfuration agent.Under the optimal reaction conditions,23 kinds of2-mercaptobenzopentazole compounds were synthesized in a yield of 30-95%.The feature of this work is,short reaction time?10-30 min?,“one-pot”manner?as few steps as possible,no need to isolate the intermediates?.3.A synthetic method for the H₂O-mediated preparation of2-mercaptobenzopentazoles?2-mercaptobenzothiazoles,2-mercaptobenzoxazoles,benzimidazole-2-thiones?is described.Under the optimal reaction conditions,31kinds of 2-mercaptobenzopentazole compounds were synthesized in 31-95%yields.Compared with our previous work?Al Cl₃-mediated?,the method uses a cheap and easy-to-use,stable tetramethylsulfate disulfide disulfide reagent,which does not require any catalyst.Furthermore,it also features higher yield,water as solvent,which is an economic green synthetic method.4.A copper-catalyzed S-arylation three-component reaction was developed using a bifunctional compounds?o-aminothiophenol,o-aminophenol?,tetramethylthiuram disulfide,and aryl iodides as a substrate.Under the optimal reaction conditions,a series of 17 2-S-arylbenzothiazoles were synthesized in 62-87%yields,16 kinds of2-S-arylbenzoxazoles were synthesized in 40-85%yields.The method has advantages of inexpensive catalysts and ligands,milder reaction conditions,three-component one-pot manner,water as a solvent,showing its high efficiency in organic synthesis.5.Selective Chan-Lam coupling reaction of benzimidazole-2-thiones with arylboronic acids was developed.A series of 1-N-aryl-2-S-arylbenzimidazoles and2-S-arylbenzimidazoles compounds were selectively synthesized by varying the amount of copper catalyst.Under the optimal reaction conditions,14 kinds of1-N-aryl-2-S-arylbenzimidazoles were obtained in 30-91%yields,16 kinds of2-S-arylbenzimidazoles in 52-95%yields.The protocol features inexpensive catalysts and ligands,no need to use inert atmosphere,good selectivity and good yields.