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 40c,d
Wade 9th EditionCh. 22 - Condensations and Alpha Substitutions of Carbonyl CompoundsProblem 40c,dChapter 22, Problem 40c,d
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) 
Verified step by step guidance1
Step 1: Understand the Dieckmann condensation reaction. It is an intramolecular reaction where a diester undergoes base-catalyzed cyclization to form a β-keto ester. This reaction requires the diester to have two ester groups separated by a suitable number of carbons to form a stable ring.
Step 2: Analyze structure (A). The product shown is a bicyclic β-keto ester. To form this structure via Dieckmann condensation, the starting diester must have two ester groups positioned such that cyclization forms the bicyclic ring system. Verify if the ester groups are appropriately spaced for cyclization.
Step 3: Analyze structure (B). The product shown is a monocyclic β-keto ester. To form this structure via Dieckmann condensation, the starting diester must have two ester groups positioned such that cyclization forms the six-membered ring. Check if the ester groups are appropriately spaced for cyclization.
Step 4: Draw the starting diesters for both (A) and (B). For (A), the diester should have ester groups on carbons that allow formation of the bicyclic system. For (B), the diester should have ester groups on carbons that allow formation of the six-membered ring.
Step 5: Confirm the feasibility of the Dieckmann condensation for each structure. Ensure that the reaction conditions (base and solvent) would favor cyclization and that the resulting rings are stable (e.g., five- or six-membered rings are preferred).
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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 type of intramolecular Claisen condensation 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 or a cyclic compound. Understanding the conditions and mechanisms of this reaction is crucial for determining which keto esters can be synthesized from given diesters.
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Diesters (Dieckmann Condensation)
Keto Esters
Keto esters are organic 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 structure and reactivity of keto esters are important in organic synthesis, particularly in reactions like Dieckmann condensation, where they can serve as intermediates or products.
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Starting Diesters
Starting diesters are the initial compounds used in the Dieckmann condensation process. They typically contain two ester functional groups that can react under basic conditions to form a cyclic product. Identifying the correct starting diesters is essential for predicting the possible keto esters that can be formed, as the structure and arrangement of these diesters influence the outcome of the reaction.
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Related Practice
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)
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Textbook Question
Predict the products from crossed Claisen condensation of the following pairs of esters. Indicate which combinations are poor choices for crossed Claisen condensations.
(a)
(b)
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Textbook Question
Propose a mechanism for the crossed Claisen condensation between ethyl acetate and ethyl benzoate.
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.
Textbook Question
Predict the products from crossed Claisen condensation of the following pairs of esters. Indicate which combinations are poor choices for crossed Claisen condensations.
(c)
(d)
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