Textbook Question
Suggest a synthetic scheme, involving a protecting group, to generate the molecule shown starting with the molecule at the left.
(c)
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Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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Table of contents
- Ch. 2 - General Chemistry Translated: Finding the Electrons114
- Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis109
- Ch. 4 - Acids and Bases: Electron Flow144
- Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics118
- Ch. 6 - Stereoisomerism: Arrangement of Atoms in Space112
- Ch. 7 - Principles of Green (Organic) Chemistry3
- Ch. 8 - Alkenes I: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes II: Oxidation and Reduction150
- Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions101
- Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions108
- Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes172
- Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination239
- Ch. 14 - Structural Identification I: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution I: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution II: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems I: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems II: Pericyclic Reactions54
- Ch. 23 - Benzene I: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring62
- Ch. 25 - Amines: Structure, Reactions, and Synthesis27
- Ch. 26 - Amino Acids, Proteins, and Peptide Synthesis9
- Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids54
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
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Mullins 1st EditionCh. 17 - Carbonyl Addition Reactions: Aldehydes and KetonesProblem 67
Mullins 1st EditionCh. 17 - Carbonyl Addition Reactions: Aldehydes and KetonesProblem 67Chapter 16, Problem 67
As discussed in Section 17.9.1, alkenes can be hydrogenated selectively in the presence of ketones. Suppose that was not the case, and suggest how you might use a protecting group strategy to generate A from B.
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Identify the functional groups in compound B. It contains an alkene and a ketone group. The goal is to selectively hydrogenate the alkene without affecting the ketone.
Consider using a protecting group strategy to shield the ketone from hydrogenation conditions. A common protecting group for ketones is the acetal, which can be formed by reacting the ketone with a diol under acidic conditions.
React compound B with a diol, such as ethylene glycol, in the presence of an acid catalyst to form the acetal protecting group. This will temporarily convert the ketone into an acetal, which is stable under hydrogenation conditions.
Perform the hydrogenation reaction on the alkene. Use a catalyst like palladium on carbon (Pd/C) under hydrogen gas to selectively reduce the alkene to an alkane while the ketone is protected as an acetal.
Finally, remove the acetal protecting group by hydrolysis. Treat the compound with aqueous acid to regenerate the ketone from the acetal, yielding compound A.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hydrogenation of Alkenes
Hydrogenation is a chemical reaction that involves the addition of hydrogen (H2) to an alkene, converting it into an alkane. This process typically requires a catalyst, such as palladium or platinum, and can be selective, meaning it can target specific double bonds in the presence of other functional groups. Understanding the conditions and selectivity of hydrogenation is crucial for manipulating alkenes in organic synthesis.
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The definition of hydrogenation.
Protecting Groups
Protecting groups are temporary modifications used in organic synthesis to shield reactive functional groups from undesired reactions during a multi-step synthesis. By selectively protecting certain groups, chemists can control the reactivity of molecules, allowing for specific transformations without interference. This strategy is essential when dealing with complex molecules that contain multiple functional groups.
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Functional Group Interconversion
Functional group interconversion refers to the process of transforming one functional group into another within a molecule. This concept is fundamental in organic chemistry as it allows chemists to modify the reactivity and properties of compounds. Understanding how to effectively perform these conversions is key to designing synthetic pathways, especially when protecting groups are involved.
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Related Practice
Textbook Question
We show in Chapter 20 that α , β-unsaturated ketones are electrophilic at C4. Rationalize this observation.
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Textbook Question
Suggest a synthetic scheme, involving a protecting group, to generate the molecule shown starting with the molecule at the left.
(d)
834
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Textbook Question
When a ketone is dissolved in 18O-labeled water, the 18O label is incorporated into the ketone. Suggest a mechanism that explains this observation.
875
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Textbook Question
Suggest a synthetic scheme, involving a protecting group, to generate the molecule shown starting with the molecule at the left.
(b)
806
views