Mislow–Evans rearrangement

General reaction scheme

The reaction allows the formation of allylic alcohols from allylic sulfoxides by a 2,3-sigmatropic rearrangement. The conversion can be highly diastereoselective as the chirality at sulphur atom can be transmitted to the carbon next to the oxygen in the product.

The sulfoxide 1 reagent can be generated easily and enantioselectively from the corresponding sulfide by an oxidation reaction. In this reaction various organic groups can be used, R1 = alkyl, allyl and R2 = alkyl, aryl or benzyl

Mechanism

A proposed mechanism is shown below:

The mechanism starts with an allylic sulfoxide 1 which undergoes a thermal 2,3-sigmatropic rearrangement to give a sulfenate ester 2. This can be cleaved using a thiophile, such as phosphite ester, which leaves the allylic alcohol 3 as the product.

Scope

The reaction has general application in the preparation of trans-allylic alcohols. Douglass Taber used the Mislow–Evans rearrangement in the synthesis of the hormone prostaglandin E2.

References

References

1. (2006). "Name Reaction". [[Springer Publishing]].
2. (1966). "Mechanisms of Thermal Racemization of Sulfoxides". Journal of the American Chemical Society.
3. (1971). "Reversible 1,3 transposition of sulfoxide and alcohol functions. Potential synthetic utility". Journal of the American Chemical Society.
4. (2005). "Strategic applications of named reactions in Organic Synthesis". [[Elsevier]].
5. (1974). "Allylic sulfoxides. Useful intermediates in organic synthesis". Accounts of Chemical Research.
6. (2009). "''Comprehensive Organic Name Reactions and Reagents''". John Wiley & Sons.