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3.7.1.6 The Eschenmoser–Claisen Rearrangement

DOI: 10.1055/sos-SD-203-00213

Zeh, J.; Hiersemann, M.Science of Synthesis: Stereoselective Synthesis, (20113360.

Dialkylamino-substituted allyl vinyl ethers generated in situ undergo the EschenmoserClaisen rearrangement at elevated temperatures to afford γ,δ-unsaturated amides.[‌14‌] Forcing conditions are required to form the intermediate O-allyl ketene N,O-acetal from the allylic alcohol by a transacetalizationelimination reaction. Nevertheless, many functional groups are tolerated, as this variant does not require the presence of additional basic or acidic additives. Moreover, the EschenmoserClaisen rearrangement is particularly successful for cases where there is a build-up of steric strain, e.g. in the synthesis of quaternary chiral carbon atoms. In comparison with the IrelandClaisen and JohnsonClaisen rearrangement (see Sections 3.7.1.7 and 3.7.1.8, respectively), this type of Claisen rearrangement provides improved yields and selectivities.

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