Portal de Periódicos da CAPES

Stereospecific Deoxygenation of Epoxides to Olefins

1987; Elsevier BV; Volume: 26; Issue: 5 Linguagem: Inglês

10.3987/r-1987-05-1345

1881-0942

Henry Ν. C. Wong, Charles C. M. Fok, Man Kong Wong,

Eicosanoids and Hypertension Pharmacology

AbsLracr -Various methods for stereospecific deoxygenation of &oxides t o olefins are presented.The mechanisms involved in these transformations will also be discussed.i -Deoxygenation of epoxides to olefine has aroused great interest.In the paet three decades, chemists have shown great enthusiasm to methods which are able to increase the yields as well as to control the stereochemistry of these reactions, so that they may become more feasible.Subsequently, a great many improvements in the stereospecificity of these reactions have been recorded.Deoxygenation of epoxides to olefins remains as one o f the mast impartanr transformations in organic synthesie, because structure elucidation of complelc organic molecules, as well as inversion of the 1 geometry of carbon-carbon double bonds can be aeeomplished.To this connection, &-olefin Q) and =-olefin Q) can undergo epoxidation to &-epaxide (Z) and trans-epoxide Q ) respectively.When appropiate deoxygenation reagent is employed, &-epoxide (Z) and =-epoxide Q) can be converted to the corresponding =-olefin Q ) and &-olefin Q ) respectively. 1 deoxygenation with retention r: oxidation R -R (A ) deoxygenation with inversion b oxidation deoxygenation .with inversion oxidation n deoxygenetion R H ($) with retention d oxidation Furthemre, a number of reagents have been found to possess ability of deoxygenation &-epoxide (Z) and =-epaxide Q ) to accordingly *-olefin Q ) and --olefin Q).The term "retention" is used t o describe the geometry of this conversion, which is extremely useful in the strveture elucidation of complex nstliral'produets containing epoxide linkage.In the following text, we would briefly review some of the multi-step procedures which can produce olefins from epoxides stereospecifically or "on-stereospecifically.Then some reagents which are capable of deoxygenating,epoxidee to olefine "on-stereospecifically will be given in Table 4. Flnally, rhe Ieagenrs and their meehanisns for the one-step epoxide stereospecific deoxygenarion to olefin will be discussed in details.Table 1 ehows the brief layout of this review.