Epoxy Ramberg-Backlund reaction

The epoxy-Ramberg-Backlund reaction (ERBR) has been used for the conversion of a,/3-epoxy sulfones into a range of mono-, di-, and tri-substituted allylic alcohols.34 Modification of this method has permitted the preparation of enantio-enriched allylic alcohols following the diastereoselective epoxidation of enantio-enriched vinyl sulfones that were accessed efficiently from the chiral pool. 

Treatment of o ,/ -epoxysulfones with bases, such as KO-/-Bu, lithium diisopropylamide (LDA), LiHMDS, or LiO-/-Bu in THE, led to the epoxy-Ramberg-Backlund reaction and gave allyl alcohols via thiirane 1,1-dioxides (HMDS = hexamethyldisilazide). The latter lose sulfur dioxide under the reaction conditions (Scheme 22) <1997TL3055>. 

Evans, P., Taylor, R. J. The epoxy-Ramberg-Backlund reaction a new route to allylic alcohols. Tetrahedron Lett. 1997, 38, 3055-3058. Evans, P., Taylor, R. J. K. Novel tandem conjugate addition/Ramberg-Backlund rearrangements. Syniett 1997,1043-1044. 

Epoxy Ramberg-Backlund Reaction. c/j/ -Epoxy sulfones... 

A novel tandem process has been reported " for the preparation of allylic amines, ethers, and sulfides from a-bromo-a, jS-unsaturated sulfones. The process is believed to proceed via an initial conjugate addition followed by proton exchange and Ramberg-Backlund rearrangement (see Scheme 75). A new variant of the Ramberg-Backlund reaction has been described in which a, /f-epoxy sulfones (319), on treatment with base, are converted into a range of mono-, di-, and tri-substituted allylic alcohols (320). 

Alfylicalcohols. Epoxy sulfones undergo the Ramberg-Backlund reaction in which the epoxide acts as the leaving group. Decomposition of hydroxylated episulfones affords the allylic alcohols. 

Numerous variants of the Ramberg-BScklund reaction exist. The most prevalent are the vinylogous and Michael-induced Ramberg-BScklund reactions. Decarboxy-lative, epoxy-, and tandem Diels-Alder Ramberg-Backlund reactions are also found in the literature. 

Epoxy-Ramberg-BScklund reaction is also uncommon. In place of iodide, sulfonate, or sulfinate leaving groups, Taylor and his colleagues chose epoxide as the leaving group in the Ramberg-Backlund reaction.28 As shown below, exposure of... 

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