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12.S: Reactions at the α-Carbon, Part I (Summary)

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    Before moving on to the next chapter, you should:

    • Understand what is meant by 'a and b positions' relative to a carbonyl group.
    • Understand how an enzyme can increase the acidity of an a-proton through the active site microenvironment
    • Understand the 3D bonding arrangement of an enolate ion
    • Be able to recognize and draw reasonable mechanisms for the following reaction types:
      • tautomerizations: keto-enol, imine-enamine
      • racemization/epimerization
      • carbonyl isomerization (changing position of a carbonyl group)
      • alkene isomerization (changing position of an alkene relative to carbonyl)
      • aldol addition, retro-aldol cleavage (both enolate intermediate and enamine intermediate mechanisms)
    • Be able to draw a mechanism for a laboratory alkylation reaction at the a-carbon of a ketone or aldehyde. Understand the difference between kinetic and thermodynamic control of this reaction type, and be able to predict the regiochemical outcome of the reaction based on reaction conditions.

    This page titled 12.S: Reactions at the α-Carbon, Part I (Summary) is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Tim Soderberg via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.