Science of Synthesis

Zeh, J.; Hiersemann, M., Science of Synthesis: Stereoselective Synthesis, (2011) 3, 360.

Dialkylamino-substituted allyl vinyl ethers generated in situ undergo the Eschenmoser–Claisen 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 transacetalization–elimination reaction. Nevertheless, many functional groups are tolerated, as this variant does not require the presence of additional basic or acidic additives. Moreover, the Eschenmoser–Claisen 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 Ireland–Claisen and Johnson–Claisen 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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References