Textbook Question
Propose mechanisms for the two Dieckmann condensations just shown.
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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 40
Wade 9th EditionCh. 22 - Condensations and Alpha Substitutions of Carbonyl CompoundsProblem 40Chapter 22, Problem 40
Some (but not all) of the following keto esters can be formed by Dieckmann condensations. Determine which ones are possible, and draw the starting diesters.
Verified step by step guidance1
Step 1: Understand the Dieckmann condensation reaction. The Dieckmann condensation is an intramolecular Claisen condensation where a diester reacts with a base to form a cyclic β-keto ester. This reaction typically forms 5- or 6-membered rings due to favorable ring strain considerations.
Step 2: Analyze each keto ester provided in the problem. Check the structure of each keto ester to determine if it can be formed by an intramolecular reaction that results in a 5- or 6-membered ring. Larger or smaller rings are generally not favored due to ring strain.
Step 3: For each keto ester that can form a 5- or 6-membered ring, identify the corresponding starting diester. The starting diester should have two ester groups positioned such that they can react intramolecularly to form the desired ring size.
Step 4: For keto esters that cannot form 5- or 6-membered rings, explain why they are not possible products of a Dieckmann condensation. This could be due to unfavorable ring strain or the inability to position the ester groups appropriately for the reaction.
Step 5: Draw the structures of the starting diesters for the keto esters that are possible products of the Dieckmann condensation. Ensure that the diester structures clearly show the ester groups in positions that allow for the formation of the desired cyclic β-keto ester.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Dieckmann Condensation
Dieckmann condensation is a specific type of intramolecular aldol reaction that occurs between two ester groups in the presence of a strong base. This reaction typically leads to the formation of a β-keto ester. Understanding the mechanism involves recognizing how the base deprotonates the ester, allowing for nucleophilic attack on the carbonyl carbon of another ester group, ultimately forming a cyclic product.
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Diesters (Dieckmann Condensation)
Keto Esters
Keto esters are compounds that contain both a ketone and an ester functional group. They are characterized by the presence of a carbonyl group (C=O) adjacent to an ester group (RCOOR'). The formation of keto esters through Dieckmann condensation is significant in organic synthesis, as they can serve as intermediates for further reactions, including cyclization and functional group transformations.
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Starting Diesters
Starting diesters are the initial compounds required for the Dieckmann condensation reaction. They must have two ester groups that are capable of undergoing intramolecular reaction. The structure and positioning of these ester groups are crucial, as they determine whether the condensation can occur and what type of cyclic product will be formed. Identifying the correct starting diesters is essential for predicting the possible keto esters that can result from the reaction.
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Related Practice
Textbook Question
Propose mechanisms for the two Dieckmann condensations just shown.
645
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Textbook Question
Some (but not all) of the following keto esters can be formed by Dieckmann condensations. Determine which ones are possible, and draw the starting diesters.
(c)
(d)
1298
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Textbook Question
Some (but not all) of the following keto esters can be formed by Dieckmann condensations. Determine which ones are possible, and draw the starting diesters.
(a)
(b)
963
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Textbook Question
Propose a mechanism for the crossed Claisen condensation between ethyl acetate and ethyl benzoate.
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Textbook Question
Show what esters would undergo Claisen condensation to give the following β-keto esters.
(c)
1023
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