Metal-free Synthesis Of Thiocyanates And Imidazoles

Aryl thiocyanates are not only the subunits of biologically active compounds but also important intermediates to synthesize organic sulfide.However,the traditional method using cyanide as cyano source to synthesize thiocyanates is highly toxic,which severely limits the usefulness of such reactions.Recently,the method of nitrile compounds as cyanide source was developed and greatly reduced the toxicity of such reactions,but nitrile compounds containing-CN group still has a high toxicity.Imidazoles is widely present in biological macromolecules,pharmaceutical and pesticide compounds,and can also be used to synthesize materials with excellent properties,so it has a very wide range of uses.Therefore,the synthesis and application of imidazoles is still flourishing.In recent years,the transition metal-catalyzed synthesis reaction of thiocyanates and imidazoles has been made in full progress.Metal-free synthesis reaction of thiocyanates and imidazoles due to having less environmental pollution,low toxicity,broad substrateapplicability,easy to operate,economical and practical,and many other advantages,is much attention.This thesis is divided into two parts: 1.Metal-free synthesis reaction of thiocyanates.2.Metal-free synthesis reaction of imidazoles.The first part is that 18 kinds disulfide substrates containing various substituents is synthesized through the metal-free reaction,in which disulfide acts as substrate,the non-cyanide nitromethane acts as a cyanide source that in situ form a cyano.The mechanism of the reaction has been studied by TLC tracking reaction and designing control experiments,in the progress three reaction intermediates including thiosulfonate,iodide nitromethane and thiosulfate nitromethane compound were found.According to these experimental phenomena,the proposed reaction mechanism is suggested,which is carried out through two routes.The second part is that the 2-arylformylimidazole derivatives were synthesized through metal-free reaction.First,α-(N-methyl-N-phen--yl-)-arylethanone substrates is synthesized using α-aminoacetophenones as raw material.Then they react with ammonium hexafluorophosphate in an oxidizing condition.Finally,9 kinds 2-arylformylimidazole derivatives were synthesized.They were characterized by IR,GC-MS,NMR,HRMS and the melting point.In some reaction the byproduct N-methylanilinewere recycled to research.The reaction mechanism was explored.In the reaction,the ammonium source is provided by the ammonia hexafluorophosphate.Under the oxidation of silver acetate,two molecules of α-(N-methyl-N-phenyl)-arylethanone react with ammonia hexafluorophosphate,after a series of cascade reactions such as condensation,deamination,cyclization and so on,2-arylformylimidazole derivatives were obtained.