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Crossed Claisen Condensation

Last updated

Feb 28, 2022
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- Crossed Aldol Reaction
- Crosslink

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Crossed Claisen condensation is a variation of Claisen condensation.

Claisen Condensation:

Crossed Claisen Condensation:

eg:

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

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.

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

Step 5: The acid protonates enolate ion 2

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