Reaction of selenium and tellurium halides with propargyl alcohols. the regio- and stereoselectivity of addition to the triple bond

A convenient method to incorporate selenium into an organic molecule is reported. Various aspects of the reaction of SeCl₂ with propargyl alcohols, i.e., identity of reacting functionality, regiospecificity, and stereospecificity, differ from expectations based on known reactions of these alcohols with SCl₂. Selenium dihalides undergo smooth 1,2-addition to the triple bond of various propargylic alcohols resulting in the formation of the corresponding functionalized divinyl selenides in high yields and with complete regio- and stereospecificity. Of special mechanistic interest is the syn-addition and anti-Markovnikov orientation observed in all cases.