Study On The One-pot Synthesis Of Ethynyl Sulifdes Based On α-thio Carbonyl Compounds As Substrates

Ethynyl sulfides are very important intermediates in organic synthesis and can be used asversatile building blocks for a variety of chemical purposes. So it is academic and practicalsignificance to explore new methods for preparing ethynyl sulfides. The one-pot procedure,which has the advantage of simplified process, higher total yield and economical operation, isa resource-saving and environment friendly methodology and has long been an attractive areaof research. On the basis of the previous work of our lab, one-pot three-step strategy forpreparing ethynyl sulfides by-thio carbonyl compounds as substrates was developed. Mystudy can be divided into two parts entirely: the one-pot synthetic protocol of ethynyl sulfides(including arylethynyl sulfides, bis(arylethynyl) sulfides, aryl diyne sulfides and conjugatedenyne sulfides) was described in the first part; the application of ethynyl sulfides in [3+2]cycloaddition reaction was discussed in the second part.The one-pot three-step procedure for preparing arylethynyl sulfides (53a—k,54a—k,72a—k) by-thio aryl ethanone (51a—k,52a—k,71a—k) as substrates was presented forthe first time. The reagents were added to the solution of the substrates in THF sequentially asfollows: i) base; ii) ClP(O)(OEt)2; iii) base. BuLi, LiHMDS, LDA and t-BuOK werediscussed in one-pot reaction. The results showed the use of the base in the first stageinfluenced on the synthesis of arylethynyl sulfides greatly and decided the mechanism of thereaction. To obtain insight into the mechanism of this one-pot reaction, we attempted toisolate enol phosphate intermediates. A differentiated two-step procedure was performed toprove the formation of enol phosphate. The results from the1H and31P NMR spectroscopicdata reveal that the intermediate was formed in a Z/E mixture. And the Z-configuration ofmajor isomer has also been confirmed by NOESY experiment. Furthermore, we investigatedthe elimination reaction of enol phosphate intermediates, which, upon treatment theintermediates in THF with LiHMDS, occurred smoothly to provide arylethynyl sulfides.Therefore, on the basis of this evidence, we can conclude that the mechanism involves theformation of an enol phosphate and a subsequent base-induced elimination. Compared withthe double elimination mentioned, the advantage of the one-pot three-step protocol use onlyone substrate and the reagent just can be added in three stages into the system, the operationbecomes more conveniently. Additionally, the substrates can be obtained easily from arylehtanone through bromination and nucleophilic substitute reaction.The one-pot procedure for bis(arylethynyl) sulfides (92a—h) by substrates bis(arylethanonyl) sulfides (91a—h) as substrates was presented. BuLi and LiHMDS wereexamined in one-pot reaction.92h was characterized by X-ray single crystal diffraction.The one-pot procedure for aryl diyne sulfides (104a—e,105a—e and106a—e) by4-(alkylthio)-1-arylbutane-1,3-dione (101a—e,102a—e and103a—e) as substrates wasdiscussed. The ration of β-diketo and enol structures of the materials107a—h and thesubstrates in CDCl3was investigated by1H NMR. The comparation of the method to preparearyl diyne sulfides between the one-pot three-step protocol and the double elimination one-potprotocol was employed. The substrate can be obtained from aryl ethanone via condensation,bromination and nucleophilic substitute reaction.The preparation of conjugated enyne sulfides (134a—e,135a—e,136a—e) via one-potprocedure by-thio aryl substrates (131a—e,132a—e,133a—e) was described for the firsttime. The substrates can be obtained from aryl aldehydes via aldol condensatioon,bromination and nucleophilic substitute reaction. And the configuration of conjugated enynesulfides was postulated by the steic effect.The [3+2] cycloaddition reaction between phenyl ethynyl sulfides and benzyl azide wasdescribed and triazoles ((147a—b,147d—h) and148a—b,148d—h) were obtained.147aand148a were characterized by X-ray single crystal diffraction and the configuration wasdecided. The probable mechanism was postulated.In the dissertation, the idea of the one-pot three-step protocol to prepare ethynyl sulfidesby-thio carbonyl compounds as substrates was discussed by designing synthesis route,choosing appropriate base, capturing and identifying the intermediates. The one-pot procedurewill enrich the content of organic chemisty and it is significance of the application inself-assembled monolayers and related fields. All materials were characterized by1H NMR.All ethynyl sulfides and the triazoles were identified by1H NMR,13C NMR, IR, MS andHRMS.