The Formation Reaction Of C-S Bond With Isothiourea Salt And The Synthesis Of 2-mercaptobenzene-1,4-diol Derivatives

Sulfide compounds play an important role in research fields such as organic synthesis,biochemistry,and materials science.In the research of these compounds,the synthesis of C-S bond is particularly important.At present,thiol is widely used as the sulfur source for the synthesis of C-S bonds,because it often exhibits high reaction efficiency.However,thiol has an unpleasant odor,and sometimes these reactions conditions are relatively harsh,and high temperature or metal catalysis are required.Therefore,the purpose of this thesis is to find a method for the synthesis of aryl/alkyl sulfide in accordance with the concept of green chemistry.In chapter one,after surveying the literatures on the application of sulfide compounds and their preparation methods,this chapter gives a brief summary for the synthesis of sulfide from different sulfur sources.Based on our reported method of introducing thiomethyl with thiomethyl isothiourea sulfate instead of thiol,this thesis proposes the synthesis of pyrimidine sulfide using odorless and easily available isothiourea salt as a sulfur source.In chapter two,pyrimidine sulfides are widely used in medicine and natural products.It is very important to find a highly efficient synthetic method for them.After surveying relevant literatures,S-alkyl-substituted isothiourea salt as the sulfur source,which is formed by the thiourea with alkyl halides was used in this chapter.In the presence of cesium carbonate,the cyano leaving reaction was performed from 2-cyanopyrimidine and a series of pyrimidine sulfides were prepared.This method uses a wider range of alkyl halide raw materials rather than thiol.Moreover,it is important that this method can introduce polyfluoroalkyl groups into the target molecules.Isolation and purification of the product is relatively easy with few by-products,and the yield of the target product is good.These synthesized compounds in this chapter have been characterized by ¹H NMR,¹³C NMR,IR and HRMS.In chapter three,2-thiohydroquinones have widely application.Benzoquinone is used as a raw material to react with thiol for the synthesis of these compounds.In this Chapter,we are trying to replace the thiol with an isothiourea salt,but experiment shows that the expected product is not formed.Additionally,4-hydroxy-4-methoxycyclohex-2,5-dienone was formed by the reaction of p-methoxyphenol and iodobenzenediacetic acid in a mixed solvent of acetonitrile/water instead of p-benzoquinone.Several 2-alkyl/arylthio-substituted hydroquinones were synthesized without any catalyst.At the same time,the substrate range of p-methoxyphenol was expanded through the changing the solvent.The synthesized compounds in this chapter have been characterized by ¹H NMR,¹³C NMR,IR and HRMS.