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Please login to access the full content or check if you have access via The Ireland–Claisen Rearrangement

DOI: 10.1055/sos-SD-203-00213

Zeh, J.; Hiersemann, M.Science of Synthesis: Stereoselective Synthesis, (20113362.

The IrelandClaisen rearrangement is probably the most frequently used variant of the Claisen rearrangement. The required allyl vinyl ethers are generated by deprotonation of easily accessible allylic esters at low temperatures to generate the intermediate ester enolates, which are trapped as ketene silyl acetals. The 2-siloxy-substituted allyl vinyl ethers generally undergo the [3,3]-sigmatropic rearrangement upon warming to room temperature to afford γ,δ-unsaturated carboxylic acids after workup.[‌15‌] The configuration of the ketene silyl acetal double bond and, ultimately, the relative configuration of the rearrangement product can be controlled by appropriate selection of the reaction conditions. Usually, the E-enolate is obtained by performing the deprotonation/O-silylation in ethereal solvents at low temperatures, whereas strongly Lewis basic cosolvents such as hexamethylphosphoric triamide preferentially provide the Z-enolate.

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