| Selenium is not only the essential trace elements in human body, but also play animportant role in organic synthesis for its outer electron configurations. organicselenium compounds are good amphiphiles and also play as oxidants, deoxidizers, andcatalysts in many reactions. Among them, selenols, selenides and diselenides are themost basic material of organic selenium compounds, which have been used asprecursors in many other reactions. For example, alkynyl selenides are importantsubstracts in many reactions such as hydroamination, hydronhalogenation,hydroboration, hydrosulfonation and hydrostannylation in which symmetricaldialkynyl selenides are important in organic synthesis for their specal structure.Double elimination one pot method is simple and effective to construct C≡Ctriple bond. Otera et.al. have reported the preparation of aryne with-methylenesulfone and aromatic aldehydes as substrats. Our laboratory also have reported thesynthesis of arylethynyl sulfides reacted thiophanate methyl phenyl sulfone(methylthiomethyl phenyl sulfone, MP-S) with aromatic aldehydes and aromaticalkyne aldehydes by one pot method. Recently, we have synthetised arylethynylsulfides and bis(arylethynyl) sulfides successfully from arylethanonyl sulfides andbis(arylethanonyl) sulfides by a one-pot three-step strategy, respectively. Seleniumand sulfur elements are in the same main group which would obtain the similarchemical properties. Based on this, this paper mainly discusses the one-pot synthesisof dialkynyl selenides.In this article, we synthesized bis(phenylethanonyl) selenides firstly in aconvenient way in which the inexpensive and easy obtained phenylethanone reactedwith SeOCl2and was reduced by Na2S2O4subsequently. Then, the products wastreated with LHMDS and substituents to give the bis(enol-phosphate) intermediates,and add LHMDS again. After those operation, we get the a series of symmetricaldialkynyl selenides in good yields.This method has good features in short synthetic route, simple operation, highyield and inexpensive raw material which is a effective way to synthesize rareacetylide. This method is applicable for various non-proton substituting groups onthe aromatic ring (for Ar), such as methoxyl, methyl, chloro and bromo which revealthe wide applicability of this method. On the bases of our laboratory’s researches and explorations in the process ofexperiment by myself, small changes have been made on the conditions, such as thereaction time and the selection of the leaving groups. The specific operation of onepot method in this experiment are as follows: under an atmosphere of nitrogen,LHMDS (1.2mL,1.0mol·L-1in THF/Ethylbenzene) was added to a solution ofbis(arylethanonyl) selenides (1.0mmol) in THF (15mL) at78oC, and the mixturewas stirred for30min. Then ClP(O)(OPh)2(0.31mL,1.1mmol) was added dropwiseat78oC and the resulting mixture was warmed up to room temperature and stirredfor1.5h. The reaction mixture was cooled to78oC and then LHMDS (2.5mL,1.0mol·L-1in THF/Ethylbenzene) was added. After being stirred at this temperature for1h, the reaction was quenched with aqueous NH4Cl solution and the crude products wassubsjected to flash column chromatography (petroleum ether as eluent) to givebis(arylethynyl) selenides.In order to gain insight into this one-pot reaction, we have tried to investigate themechanism of this one-pot reaction, and the main work is to obtain the keyintermediates and the analysis of its structure based on which we propose the rationalreaction mechanism.All the intermediates were characterized by1H NMR,13C NMR and thecompounds not ever reported were further confirmed by MS and HRMS. All the targetcompounds synthesized in this paper were characterized by HRMS, MS, IR,1H NMRand13C NMR. |
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