Enamine Synthesis
Enamine Synthesis - Related Videos
01:26
Synthesis of α-Substituted Carbonyl Compounds: The Stork Enamine Reaction
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2025
α-Substituted ketones or aldehydes can be synthesized from enamines by the Stork enamine reaction, named after its pioneer Gilbert Stork. Enamines are useful synthetic intermediates where the lone pair on nitrogen is in conjugation with the C=C bond. They resemble enolate ions, as the resonance forms of both species have a nucleophilic α carbon. However, enamines are neutral and less reactive than enolates, which bear a net negative charge. Consequently, enamines are effective Michael donors...
01:14
Aldehydes and Ketones with Amines: Enamine Formation Mechanism
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2025
Enamine formation involves the addition of carbonyl compounds to a secondary amine through a series of reactions. The mechanism begins with the generation of carbinolamine, a nucleophilic attack followed by several proton transfer reactions. The hydroxyl group of the carbinolamine is converted into water to make a better leaving group that can push the reaction forward by eliminating a water molecule. In enamine formation, the last step involves the abstraction of a proton from the α carbon to...
01:16
Aldehydes and Ketones with Amines: Imine and Enamine Formation Overview
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2023
Primary amines react with carbonyl compounds—aldehydes and ketones—to generate imines. Imines consist of a C=N double bond and are named Schiff bases after its discoverer—the German chemist Hugo Schiff. On the other hand, secondary amines react with carbonyl compounds to give enamines. In enamines, the presence of a C=C double bond adjacent to the nitrogen atom leads to the delocalization of the lone pair. Both imine formation and enamine formation are reversible and acid-catalyzed.
08:33
Hydrogel Synthesis
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2023
Source: Amber N. Barron, Ashlea Patterson, and Taylor D. Sparks, Department of Materials Science and Engineering, The University of Utah, Salt Lake City, UT Hydrogels are a versatile class of cross-linked polymers produced through relatively simple procedures and with generally inexpensive materials. They can be formed from solution and involve a polymer backbone formed from monomer reagents, an initiator which makes the polymer reactive and a crosslinking species which binds the polymer chains...
09:42
Solid Phase Synthesis
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2023
Source: Vy M. Dong and Diane Le, Department of Chemistry, University of California, Irvine, CA Merrifield's solid-phase synthesis is a Nobel Prize winning invention where a reactant molecule is bound on a solid support and undergoes successive chemical reactions to form a desired compound. When the molecules are bound to a solid support, excess reagents and byproducts can be removed by washing away the impurities, while the target compound remains bound to the resin. Specifically, we will...
FAQs
Acid catalysis facilitates condensation between the carbonyl compound and the secondary amine, while the reaction equilibrium can be encouraged by removing water. These conditions help drive formation of the enamine intermediate rather than leaving the starting aldehyde or ketone unchanged. In practice, water removal is therefore a key part of obtaining a useful reactive intermediate.
The enamine shifts useful electron density toward the alpha carbon, the carbon adjacent to the original carbonyl carbon. That location can attack an electrophile, allowing a new carbon-carbon bond or an acyl-derived substitution to be introduced. The nitrogen-containing intermediate therefore provides a way to functionalize the carbonyl compound at its alpha position.
Hydrolysis converts the nitrogen-containing intermediate back into a carbonyl compound after the electrophile has been incorporated. Because the new substituent remains attached to the alpha carbon during this conversion, the sequence delivers an alpha-substituted aldehyde or ketone. This regeneration separates the temporary activating group from the final carbonyl product.
The sequence begins by combining an aldehyde or ketone with a secondary amine under acid-catalyzed condensation conditions, often while removing water. The resulting enamine is then exposed to an electrophile to form the desired carbon-carbon bond or acylated product. Finally, hydrolysis removes the nitrogen-containing component and regenerates the modified carbonyl compound.
The strategy temporarily converts a carbonyl compound into a form that reacts through its alpha carbon with an electrophile. This organized sequence supports introduction of an alkyl or acyl substituent before the carbonyl group is restored by hydrolysis. Such control is valuable when constructing more complex molecules from aldehyde or ketone starting materials.
Enamine synthesis is useful in medicinal chemistry, natural product synthesis, and mechanistic studies. In molecule-building research, its alpha-functionalization sequence helps create more complex carbon frameworks from carbonyl compounds. In mechanistic work, the formation, electrophilic reaction, and hydrolytic regeneration provide a defined sequence for examining how carbonyl compounds are transformed.