Research On The (Fluoro) Alkylselenylation And (Fluoro) Alkyltellurolation Reaction

Selenium-and tellurium-containing compounds have very important applications in the fields of medicine,pesticide,synthesis and materials.Therefore,the synthesis of organoselenium and organotellurium compounds is particularly important in organic synthesis.In this thesis,new methods for the synthesis of organoselenium and organotellurium compounds were developed by using sodium selenites（Na Se O₂R）and sodium aryltellurites（Na Te O₂R）,which is odorless,stable,cheap and easy-to-obtain in large quantities.In addition,combined with the advantages of fluorine-containing compounds,monofluoromethyl selenoethers were constructed for the first time through a one-pot multi-step reaction.After replacing the selenium source with sulfur source,a new route for the construction of monofluoromethyl sulfides were successfully developed.Furthermore,we successfully constructed the C-Te C₂F₅ bond by Cu Te C₂F₅,which was generated in situ.Firstly,a series of sodium selenites（Na Se O₂R,R=CH₃,Aryl）were synthesized,and the selenylation of sodium selenites with indoles under reduction condition was studied.The yields of desired products were 46%-90%.The results showed that diselenide（RSe Se R）would be generated from Na Se O₂R in the presence of（Me O）₂P（O）H.Then Cu Cl would serve as a catalyst for transformation of RSe Se R,to afford RSe^-and RSe⁺.Then RSe⁺would attack the indole to construct the C-Se R bond（R=CH₃,Aryl）.In the same system,sodium selenites can also react with furan,pyrrole and ketone compounds to construct the corresponding products in 57%,41%and 58%-87%yields,respectively.Good yields and a broad functional group compatibility were observed.After the successful synthesis and applications of sodium selenites,a series of sodium aryltellurites were further synthesized.The reaction for the synthesis of diaryltelluride from sodium aryltellurites and arylazo sulfones under the reduction condition were studied.The synthesis of sodium aryltellurites is simple and can be prepared in large quantities.Sodium aryltellurites were transformed to diaryl ditellurides in reductive condition,the aryl radical ultimately reacts with diaryl ditellurides to provide the corresponding diaryl tellurides.The reaction conditions are simple,mild,good yields（46%-96%）and a broad functional group compatibility were observed.This reaction was not only suitable for different aryl diazo salts,but also suitable for different sodium aryltellurites.Considering the importance of fluorine-containing compounds,a one-pot multi-step reaction using KSe CN and ICFH₂for the monofluoromethylselenolation of aryl and alkyl halides was developed,a series of monofluoromethyl selenothers products were synthesized in 47%-93%yields for the first time.The reactions start with amines or alkyl bromides to construct the corresponding C（sp2）-Se CFH₂ or C（sp3）-Se CFH₂ bonds.Using KSCN instead of KSe CN can also construct the monofluoromethyl sulfides in 53%-92%yields.The reactions are easy to handle,broad substrate scope,wide functional groups,and can be applicative in late-stage monofluoromethylselenolation of drug-like compounds.Finally,the construction of Te C₂F₅-containing compounds was developed,a series of pentafluoroethyltelluride products were synthesized in 53%-92%yields for the first time.In this reaction,the Cu Te C₂F₅ was generated in situ and reacted with benzyl bromides to construt the C-Te C₂F₅ bond.The yields were good when benzyl bromides containing electron-withdrawing groups,but decreased when the electron-donating group was present.