ALKENES FROM CYCLIC SULFATES AND THIONOCARBONATES OF 1,2-DIOLS VIA TELLURIUM CHEMISTRY

Treatment of 1,2-diol cyclic sulfates (1,3,2-dioxathiolane 2,2-dioxides) with telluride ion, generated in situ by reduction of the element, yields alkenes rapidly (10 min- 2 h) under mild conditions (0 degrees C to room temperature). The reaction is stereospecific, e.g. meso-2,3-diphenylethane 2,3-diol --> cis-stilbene; d,1-2,3-diphenylethane-2,3-diol --> trans-stilbene. Unsaturated mannose and ribose derivatives have been obtained and diethyl (-)-tartrate gives diethyl fumarate. The reaction may be performed with 0.1 equiv or less of elemental tellurium in the presence of a stoichiometric amount of reducing agent Reaction of telluride ion with cyclic thionocarbonates (1,3-dioxolane-2-thiones) of meso- and d,l-1,2-dipbenylethane-1,2-diol yields cis- and trans-stilbene, respectively.