Stereoselective bifunctionalization of alkynes by means of the mercury(II) salt–iodine combination

Abstract

The reaction of alkynes with iodine and mercury(II) salts (chloride, acetate, methanesulphonate, toluene-p-sulphonate, benzyl sulphide, toluene-p-sulphinate, and thiocyanate) affords stereoselectively E-β-functionalized vinyl iodides resulting from the ionic addition of iodine and the mercury(II) salt anion. Unsymmetrical alkynes yield regiospecifically Markovnikov addition products. In the case of mercury(II) thiocyanate the reaction can be used also for the stereoselective preparation of E-1,2-dithiocyanatoalkenes. An ionic mechanism is proposed according to the observed regio- and stereochemistry.