Wharton rearrangement

What is Wharton rearrangement?

The Wharton rearrangement, also known as the conversion of α,β-epoxy ketones (or ketoepoxides) into allyl alcohols, was initially discovered by Wharton in 1961. The reaction is carried out by reducing α,β-epoxy ketones with an excess amount of hydrazine.

Wharton rearrangement - general reaction scheme - hydrazine
Wharton rearrangement

R, R’ = alkyl, aryl
The α,β-epoxy ketones are typically prepared through the epoxidation of allyl alcohol with m-CPBA, followed by the Parikh-Doering oxidation (SO/ pyridine / DMSO) or by treating α,β-unsaturated ketones with alkaline hydrogen peroxide (i.e., the Weitz-Scheffer epoxidation, e.g., H2O/ NaOH).

During the Wharton rearrangement, the configuration of the starting epoxide is retained in the new-forming alcohol, and the newly formed C=C double bond in allyl alcohol is generally in the trans-configuration. The reaction typically yields good to almost quantitative yields (by NH2NH2 in acetic acid), but it may not work for certain fused molecules, such as tricyclo[7.1.1.02,7]undecane (see list of acronyms).

References

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