Cyclic thionocarbonate, Corey-Winter olefin

The Corey-Winter olefin synthesis is a two-step transformation of a diol 1 to an olefin 3.1"3 A cyclic thionocarbonate 2 is prepared from the diol 1, and subsequent heating of 2 with phosphite affords olefin 3. 

By application of the Corey-Winter reaction,vicinal diols 1 can be converted into olefins 3. The key step is the cleavage of cyclic thionocarbonates 2 (1,3-dioxolanyl-2-thiones) upon treatment with trivalent phosphorus compounds. The required cyclic thionocarbonate 2 can be prepared from a 1,2-diol 1 and thio-phosgene 4 in the presence of 4-dimethylaminopyridine (DMtVP) ... 

Cyclic thionocarbonates (41) can be cleaved to olefins (the Corey-Winter reaction)274 by heating with trimethyl phosphite275 or other trivalent phosphorus compounds276 or by treatment with bis(l,5-cyclooctadiene)nickeI.277 The thionocarbonates can be prepared by treatment of 1,2-diols with thiophosgene and 4-dimethyIaminopyridine (DMAP) 278... 

Olefin synthesis. Corey and Winter" devised a novel olefin synthesis from 1,2-diols utilizing in the first step the reaction with thiocarbonyldiimidazole (2), a reagent prepared from 2 moles of imidazole and 1 mole of thiophosgene. Corey postulated that treatment of the cyclic thionocarbonate (3) with a reagent which would abstract sulfur to form the curbenc (4) would effect cis elimination to the olefin and found that trimethyl phosphite effects this reaction cleanly and in high yield. [Pg.1350]

In 1963, Corey and Winter disclosed their discovery of a new method for the stereospecific synthesis of olefins from 1,2-diols. Treatment of mejo-hydrobenzoin 4 with carbonyldiimidazole in toluene at reflux gave the corresponding cyclic thionocarbonate 5 with quantitative conversion. Exposure of 5 to trimethylphosphite then afforded cis-stilbene 6 in 92% yield. fraHJ-Stilbene could be obtained by starting with the corresponding tram-diol. This two-step reaction sequence could also be used for the synthesis of cyclic olefins. Treatment of rraiw-cyclodecanediol 7 with... 

Corey-Winter elimination dibenzobarralene (442). In a similar way, spirohex-4-ene was obtained in 80% yield from (443). Daub and his co-workers have synthesized several uncommon olefins, among these (442), from parent cyclic thionocarbonates, using iron pentacarbonyl as the efficient elimination promoter. Semmelhack and Stauffer have reported that bis-(cyclo-octa-l,5-diene)nickel (444) converts thionocarbonates of vic-diols into the corresponding olefins in excellent yields and with a high degree of stereospecificity. In connection with a discussion of the mechanistic pathways of this reaction, the authors presented evidence for the intermediacy of the carbene complex (445). 

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