Dearomative [2,3] sigmatropic rearrangement of ammonium ylides

What is it about?

The dearomative [2,3] sigmatropic rearrangement followed by 1,4-elimination of ammonium ylides to provide alpha-(ortho-vinylphenyl)amino acid esters was successfully demonstrated.

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Why is it important?

[2,3] Sigmatropic rearrangements involving an aromatic C=C double bond, such as a Sommelet–Hauser rearrangement, is a unique synthetic transformation because the rearrangement enables the generation of a dearomatized cyclohexadienyl derivative; however, the synthetic applications of these reactions have been limited. Our group found the base-promoted 1,4-elimination from the cyclohexadienyl derivatives proceeded in situ to form alpha-(ortho-vinylphenyl)amino acid esters.