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Malonic Ester Synthesis

[ "article:topic", "authorname:ggunawardena", "Malonic Ester Synthesis" ]
  • Page ID
    40649
  • Malonic ester synthesis is a synthetic procedure used to convert a compound that has the general structural formula 1 into a carboxylic acid that has the general structural formula 2.

    • R1 = alkyl group
    • L = leaving group

    The group —CH2CO2H in 2 is contributed by a malonic ester, hence the term malonic ester synthesis.

    • R2 = alkyl, aryl

    Malonic ester synthesis consists of four consecutive reactions that can be carried out in the same pot.

    eg:

    reaction 1:

    reaction 2:

    reaction 3:

    reaction 4:

    A more direct method to convert 3 into 4 is the reaction of 3 with the enolate ion (5) of ethyl acetate followed by hydrolysis of the resultant ester.

    However, the generation of 5 from ethyl acetate quantitatively in high yield is not an easy task because the reaction requires a very strong base, such as LDA, and must be carried out at very low temperature under strictly anhydrous conditions.

    Malonic ester synthesis provides a more convenient alternative to convert 3 to 4. Malonic ester synthesis can be adapted to synthesize compounds that have the general structural formula 6.

    • R3, R4 = identical or different alkyl groups

    eg:

    reaction 1:

    reaction 2:

    reaction 1 (repeat):

    reaction 2 (repeat):

    reaction 3:

    reaction 4:

    see also acetoacetic ester synthesis