Sigmatropic rearrangements oxyanion-accelerated

The chemistry of the divinylcyclobutanols derived from 5-methylenespiro[3.5]nonanone (260) proved to be more complicated than the reactions described above. As expected, the oxyanion-accelerated 3,3-sigmatropic rearrangement of the cis isomer (261) was extremely f acile as a consequence of the rigid j-cis orientation of the exocyclic methylene group (Scheme 35). The rearrangement of the trans isomer, however, produced none of the desired Cope product instead this cyclobutanol salt underwent exclusive 1,3-rearrangement to afford the cyclohexenol derivative (264). It is uncertain whether this transformation... 

The ability of charged substituents to accelerate the 3,3-sigmatropic rearrangement of allyl vinyl ethers (the Claisen rearrangement) has also been documented. The effect of oxyanion substituents on the rate and course of aliphatic Claisen rearrangements has been the subject of particular attention. - In 1972, Ireland and Mueller reported that the lithium enolate derivatives of allyl esters undergo rapid and effi-... 

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