Cesium Base Promoted Synthesis Of Alkynyl Selenides(Tellurides) And Stereoselective Synthesis Bissubstituted Vinyl Sulfides

Cesium base is a kind of super stronger inorganic bases, it can seize hydrogen of terminal alkyne to give a steady alkyne anion, then alkyne anion attacked electrophilic reagents, get corresponding alkynyl compounds. Chalcogenide (S, Se, Te) have a empty 4d orbit, it's tend to become stableα-carbon anion. These characteristics make organic chalcogenide as a kind of reagents, there is indispensable function in organic synthesis.Alkynyl selenides and alkynyl tellurides are a type of important intermediate in organic synthesis, the methods of the literature reported synthesize alkynyl selenides and alkynyl tellurides exists currently a lot of shortage of place, some demands use expensive or toxic reagents, use not readily available reagents, some demands reaction under the low temperature (-78℃) or the heat, have strict reaction conditions, inconvenient laboratory operation. We design in the presence of a catalytic amount of cesium hrdroxide(0.2mmol), using THF as solvent, at room temperature and under an air atmosphere, diarylditellurides (1.0mmol) reacted with terminal alkynes (2.2mmol) to give exclusively alkynyl tellurides, yields 78%~90%, give the possible mechanism of the reactions. Compare with the methods of the literature reported, has its own advantages: atom economy based on tellurium, readily available staring materials, undried and nontoxic solvent, no inert atmosphere, mild conditions, and simple reaction and workup procedures. In the research of synthesize alkynyl selenides , we designed cesium hydroxide-promoted one pot reaction of terminal alkynes,element selenium and diaryliodonium salts to synthesize alkynyl arylselenides and cesium carbonate- promoted phenylacetylene,element selenium and halogenate to synthesize phenylacetylene selenides two paths. The former reaction undergo three steps, cesium hydroxide seize hydrogen of terminal alkyne at first, get stable RC≡C-Cs+ anion, then selenium inserted into carbon cesium bond and formed RC≡C-SeCs+ anion, which carried out nucleophilic substitution reaction with diaryliodonium to give corresponding asymmetry alkynyl arylselenide, yields 58%~71%. The whole procedure was performed in anhydrous DMF in the presence of 4? molecular sieves under nitrogen atmosphere. The former steps were carried out at room temperature, the third step was carried out at 0℃. The latter in the presence of chemical equivalent cesium carbonate, phenylacetylene,element selenium and halogenate reaction to give asymmetry phenylacetylene selenides via one pot, The whole procedure was performed in anhydrous DMF in the presence of 4? molecular sieves under nitrogen atmosphere, yields 63%~73%.Many articles have reported the methods of palladium catalyzed diaryl disulfides reacted with terminal alkyne synthesize vinyl sulfides, however base catalyzed diaryl disulfides addition to terminal alkyne synthesize vinyl sulfides have'nt reported at present. We design in the presence of a catalytic amount of cesium hrdroxide(0.2mmol), using THF as solvent, at room temperature and under a nitrogen atmosphere, diaryldisulfides (1.0mmol) stereoselective reacted with terminal alkynes (2.2mmol) to give (Z)-1, 2-Diarylthio-1-alkene, yields 61%~82%, but under an air atmosphere the reaction gave a mixture of alkynyl sulfide and (Z)-1, 2-diarylthio-1-alkene.