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Crossed Claisen Condensation

  • Page ID
    39397
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    Crossed Claisen condensation is a variation of Claisen condensation.

    Claisen Condensation:

    crossedclaisencondensation1.png

    Crossed Claisen Condensation:

    crossedclaisencondensation2.png

    eg:

    crossedclaisencondensation3.png

    mechanism:
    Step 1: The alkoxide ion deprotanates the enolizable ester reversibly.

    crossedclaisencondensation4.png

    Step 2 and 3: Enolate ion 1 undergoes a nucleophilic acyl substitution preferentially with the non-enolizable ester, which has the sterically less hindered and, therefore, more accessible carbonyl carbon, giving a β-ketoester.

    crossedclaisencondensation5.png

    Step 4: The alkoxide ion deprotonates the β-ketoester irreversibly.

    crossedclaisencondensation6.png

    Step 5: The acid protonates enolate ion 2

    crossedclaisencondensation7.png

    see also Dieckmann condensation


    This page titled Crossed Claisen Condensation is shared under a All Rights Reserved (used with permission) license and was authored, remixed, and/or curated by Gamini Gunawardena via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

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