Textbook Question
Propose a mechanism for the following reaction.
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Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
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Wade 9th EditionCh. 22 - Condensations and Alpha Substitutions of Carbonyl CompoundsProblem 56f
Wade 9th EditionCh. 22 - Condensations and Alpha Substitutions of Carbonyl CompoundsProblem 56fChapter 22, Problem 56f
Show how the following products might be synthesized from suitable Michael donors and acceptors.
(f) 
Verified step by step guidance1
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.
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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.
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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 how the following products might be synthesized from suitable Michael donors and acceptors.
(e)
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Textbook Question
Show how you would use Robinson annulations to synthesize the following compounds. Work backward, remembering that the cyclohexenone is the new ring and that the double bond of the cyclohexenone is formed by the aldol with dehydration. Take apart the double bond, then see what structures the Michael donor and acceptor must have.
(a)
Textbook Question
Show how the following products might be synthesized from suitable Michael donors and acceptors.
(c)
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Textbook Question
The base-catalyzed reaction of an aldehyde (having no α hydrogens) with an anhydride is called the Perkin condensation. Propose a mechanism for the following example of the Perkin condensation. (Sodium acetate serves as the base.)
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Textbook Question
Show how the following products might be synthesized from suitable Michael donors and acceptors.
(d)
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