Sulfur Mediated Difunctionalzation Of Alkynes

Activated sulfoxides have important application value in organic synthesis.The functionalization of carbon-carbon double bonds and carbon-carbon triple bonds can be realized by employing activated sulfoxides.β-haloalkenyl sulfides which can be converted into structurally complex and various vinyl sulfides and polysubstituted alkenes,have been widely utilized in materials and medicines as important organic synthetic intermediates.There are still limited for synthesizing them to date.Therefore,the development of efficient and simple synthetic strategies is of great significance to the construction of new carbon-halogen bonds and carbon-sulfur bonds.This article has researched that aryl-substituted internal alkynes could react with triflic anhydride-activated phenylethyl sulfoxides to generate sulfonium vinyl triflate intermediates,which could be converted to βbromoalkenyl sulfonium salts in the presence of tetrabutylammonium bromide by an addition-elimination fashion,and then a SN2 reaction to give β-bromoalkenyl sulfides.Therefore the formation of C(sp2)-Br and C(sp2)-S could be realized,as well as the sulfur mediated difunctionaliztion of alkynes,which provided a noval synthetic strategy for β-haloalkenyl sulfides.The reaction with good functional group tolerance,high yield,good regioselectivity and chemical stereoselectivity,could be carried out,and could been applicable to the preparation of β-chloro-and β-iodoalkenyl sulfides.In the meantime,the halothiolation product could be prepared in gram-scale,and be converted into polysubstituted alkenes efficiently by cross-coupling reactions with aryl boronic acids and phenyl grating reagenst in the presence of transition-metal catalysts.