Olefin Synthesis via Deoxygenation of Vicinal Diols

Block, Eric


Since the discovery in 1963 that 1,3-dioxolane-2-thiones (cyclic thionocarbonates) undergo stereospecific fragmentation to olefins on heating with trivalent phosphorus compounds (the Corey–Winter reaction), a variety of approaches have been developed for the regio- and stereospecific (or stereo-selective) deoxygenation of vicinal diols based on syn elimination from cyclic derivatives. These methods have been particularly useful in synthesizing substrates with delicate structural features such as strained and twisted olefins, unsaturated carbohydrates, macrocyclic lactones, lipids, and polyenes, as well as in establishing the stereochemistry of diol functions in natural products.

This chapter deals primarily with deoxygenation of vicinal diols via cyclic species with X = C, P, Ti, W, or S (suitably functionalized). Brief coverage is given to deoxygenation processes that do not involve cyclic intermediates, whereas routes proceeding via oxiranes or vic-dihalides as separately isolated intermediates are excluded from consideration. The stereochemical equilibration of vicinal diols and the conversion of vicinal hydroxy thiols and dithiols to olefins are also covered in this chapter. Brief reviews have appeared in the literature of the Corey–Winter reaction and of the general topic of deoxygenation of vicinal diols.