:Mislow–Evans rearrangement
The Mislow–Evans rearrangement is a name reaction in organic chemistry. It is named after Kurt Mislow who reported the prototypical reaction in 1966,{{Cite journal|last1=Mislow|first1=Kurt|title=Mechanisms of Thermal Racemization of Sulfoxides|journal=Journal of the American Chemical Society|year=1966|volume=88|issue=13|pages=3138–3139|doi=10.1021/ja00965a048}} and David A. Evans who published further developments.{{Cite journal|last1=Evans|first1=David A.|title=Reversible 1,3 transposition of sulfoxide and alcohol functions. Potential synthetic utility|journal=Journal of the American Chemical Society|year=1971|volume=93|issue=19|pages=4956–4957|doi=10.1021/ja00748a075}} The reaction allows the formation of allylic alcohols from allylic sulfoxides in a 2,3-sigmatropic rearrangement.{{Cite book|title=Name Reaction|url=https://archive.org/details/namereactionscol00liji|url-access=limited|last1=Li|first1=Jie Jack|publisher=Springer Publishing|year=2006|isbn=978-3-540-30030-4|page=[https://archive.org/details/namereactionscol00liji/page/n404 388]|doi=10.1007/3-540-30031-7_174}}
General reaction scheme
The reaction is a powerful way to create particular stereoisomers of the alcohol since it is highly diastereoselective and the chirality at the sulphur atom can be transmitted to the carbon next to the oxygen in the product.
File:Mislow-Evans-ÜbersichtsreaktionV2.svg
The sulfoxide 1 reagent can be generated easily and enantioselectively from the corresponding sulfide by an oxidation reaction.{{Cite book|title=Strategic applications of named reactions in Organic Synthesis|url=https://archive.org/details/strategicapplica00kurt_573|url-access=limited|last1=Kürti|first1=László|last2=Czakó|first2=Barbara|publisher=Elsevier|year=2005|isbn=9780124297852|page=[https://archive.org/details/strategicapplica00kurt_573/page/n343 292]}} 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:
File:Milslow-Evans-MechanismusV3.svg
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.{{Cite journal|last1=Evans|first1=David|last2=Andrews|first2=Glenn|title=Allylic sulfoxides. Useful intermediates in organic synthesis|journal=Accounts of Chemical Research|year=1974|volume=7|issue=5|pages=147–155|doi=10.1021/ar50077a004}}
Scope
The reaction has general application in the preparation of trans-allylic alcohols.{{citation|surname1=Zerong Wang|title=Comprehensive Organic Name Reactions and Reagents |publisher=John Wiley & Sons|location=New Jersey|pages=1991–1995|isbn=978-0-471-70450-8|date= 2009|language=German}} Douglass Taber used the Mislow–Evans rearrangement in the synthesis of the hormone prostaglandin E2.