Sulfones, allenic reaction with allylic alcohols

The adducts of the reaction of allyl alcohols with allenic sulfones are especially interesting as they allow the carbanion-accelerated Claisen rearrangement to take place. By deprotonation, or directly by addition of an allyl alcoholate anion, a system is generated, which rearranges much more easily than the uncharged system and with high diastereoselectivity (Scheme 62). 

With the exception of propadiene, the addition of sulfonyl halides and seleno-sulfonates to allenes can be totally regioselective (equation (57)) [116], The attack of sulfony] radical on the central carbon atom, which leads to a stabilized ally] radical, is probably less reversible, if at all, than the addition to the terminal carbon. The ensuing atom or group transfer occurs at the less substituted end of the allyl radical. Therefore, the reaction results in 1,2-addition to the less substituted double bond. Subsequent oxidation of the adducts when X = SePh gives rise to allylic alcohols since the [2, 3]-sigmatropic rearrangement of selenoxide is much faster than the elimination of PhSeOH. 

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