Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

25. Condensation Chemistry

Michael Addition

Organic Chemistry

25. Condensation Chemistry

Michael Addition

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2:10 minutes

Problem 56f

Textbook Question

Show how the following products might be synthesized from suitable Michael donors and acceptors.
(f)

Verified step by step guidance

Step 1: Identify the product structure. The given product is a cyclic ketone with an α,β-unsaturated side chain. This suggests that the synthesis involves a Michael addition reaction, where a nucleophilic donor adds to an α,β-unsaturated acceptor.

Step 2: Determine the Michael donor. A suitable Michael donor for this reaction would be a compound with an active methylene group, such as diethyl malonate or ethyl acetoacetate. These compounds have acidic hydrogens that can be deprotonated to form a nucleophilic enolate.

Step 3: Determine the Michael acceptor. The α,β-unsaturated side chain in the product indicates that the acceptor should be an α,β-unsaturated carbonyl compound, such as methyl vinyl ketone or acrylaldehyde.

Step 4: Outline the reaction mechanism. The Michael donor is first deprotonated using a base (e.g., NaOH or KOH) to form the enolate ion. The enolate then attacks the β-carbon of the Michael acceptor in a conjugate addition reaction, forming a new C-C bond.

Step 5: Cyclization and final product formation. After the Michael addition, the intermediate undergoes intramolecular cyclization to form the five-membered ring. This step may involve additional base or acid catalysis to facilitate ring closure and tautomerization to yield the final cyclic ketone product.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Michael Addition

Michael addition is a nucleophilic addition reaction where a nucleophile adds to an α,β-unsaturated carbonyl compound. In this reaction, a Michael donor, typically a compound with a nucleophilic site, attacks the electrophilic carbon of the double bond in the unsaturated carbonyl, forming a new carbon-carbon bond. This reaction is fundamental in organic synthesis for constructing complex molecules.

Michael Donors and Acceptors

Michael donors are nucleophiles that can donate electrons to form a bond with an electrophilic site, while Michael acceptors are typically α,β-unsaturated carbonyl compounds that can accept electrons. Common Michael donors include enolates and other nucleophilic species, whereas common acceptors include acrylates and maleimides. Understanding the nature of these species is crucial for predicting the outcomes of Michael addition reactions.

Synthesis Pathways

Synthesis pathways refer to the step-by-step methods used to construct a target molecule from simpler starting materials. In the context of Michael addition, identifying suitable donors and acceptors is essential for designing effective synthesis pathways. This involves considering the reactivity, stability, and functional groups of the reactants to achieve the desired product, as illustrated by the cyclic compound in the question.

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Related Practice

Textbook Question

Show reaction sequences (not detailed mechanisms) that explain these transformations:

(a)

Textbook Question

Show reaction sequences (not detailed mechanisms) that explain these transformations:

(b)

Textbook Question

Many of the condensations we have studied are reversible. The reverse reactions are often given the prefix retro-, the Latin word meaning “backward.” Propose mechanisms to account for the following reactions.

(c)

Textbook Question

Show how the following products might be synthesized from suitable Michael donors and acceptors.

(d)

Textbook Question

Write equations showing the expected products of the following enamine alkylation and acylation reactions. Then give the final products expected after hydrolysis of the iminium salts.

(d) piperidine enamine of cyclopentanone + methyl vinyl ketone

Textbook Question

Show how you would accomplish each conversion using an enamine synthesis with pyrrolidine as the secondary amine.

(a) cyclopentanone → 2-allylcyclopentanone

(b) pentan-3-one → 2-methyl-1-phenylpentan-3-one

Textbook Question

The following covalent inhibitor blocks function in a protease found in the porcine epidemic diarrhea virus by reacting with a cysteine amino acid residue (shown below) in the active site. Draw the expected complex that forms between the inhibitor and the enzyme active site (J. Med. Chem. 2017, 60, 3212–3216.) [Assume the presence of active site bases if you need them.]

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Textbook Question

Show how the following products might be synthesized from suitable Michael donors and acceptors.

(e)

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