Meinwald rearrangement

What is Meinwald rearrangement?

In 1963, Meinwald initially reported a reaction that is now commonly known as the Meinwald rearrangement. This reaction involves the conversion of epoxide to carbonyl compounds, specifically aldehydes or ketones, and is promoted by a Lewis acid.

Meinwald rearrangement - general reaction scheme
Meinwald rearrangement
  • R1 = alkyl, aryl
  • R2 = H, alkyl, aryl

The Lewis acids utilized in this reaction include BF3·Et2O, ZnBr2, MgBr2, InCl3, and methylaluminium bis(4-bromo-2,6-di-tert-butylphenoxide), while protic acid has also been found to be suitable. To carry out the reaction, it is typically performed under anhydrous conditions, with a stoichiometric or excess amount of Lewis acid and protection provided by an inert atmosphere.

The nature of the resulting products is determined by the migratory aptitude of the substituents attached to the epoxide moiety, the solvent used, and the Lewis acid utilized. Recently, researchers have explored the use of a catalytic amount of Lewis acid in this reaction.

References

Peracid Reactions. III.1 The Oxidation of Bicyclo [2.2.1]heptadiene2
Jerrold. Meinwald, Santokh Singh. Labana, and Mohindra Singh. Chadha
Journal of the American Chemical Society 1963 85 (5), 582-585
DOI: 10.1021/ja00888a022

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