Textbook Question
Suggest a synthetic scheme, involving a protecting group, to generate the molecule shown starting with the molecule at the left.
(a)
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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 66c
Mullins 1st EditionCh. 17 - Carbonyl Addition Reactions: Aldehydes and KetonesProblem 66cChapter 16, Problem 66c
Suggest a synthetic scheme, involving a protecting group, to generate the molecule shown starting with the molecule at the left.
(c) 
Verified step by step guidance1
Identify the functional groups in the starting material and the target molecule. The starting material has a bromo group and a ketone, while the target molecule has a hydroxyl group and a phenyl group added to the chain.
Consider the need for a protecting group. The ketone in the starting material might react during the synthesis, so it should be protected. A common protecting group for ketones is the acetal, which can be formed by reacting the ketone with a diol.
Plan the addition of the phenyl group. The bromo group can be replaced by a phenyl group through a nucleophilic substitution reaction, such as a Grignard reaction. First, convert the bromo group to a Grignard reagent by reacting it with magnesium in dry ether.
Perform the Grignard reaction. React the Grignard reagent with benzaldehyde to form the secondary alcohol. This step introduces the phenyl group and the hydroxyl group simultaneously.
Remove the protecting group. After the Grignard reaction, deprotect the ketone by hydrolyzing the acetal back to the ketone, completing the synthesis of the target molecule.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Protecting Groups
Protecting groups are chemical groups used in synthesis to temporarily mask a functional group to prevent it from reacting under certain conditions. They are crucial in multi-step synthesis to ensure that only the desired reactions occur. For example, hydroxyl groups can be protected as silyl ethers to prevent unwanted reactions during a synthesis sequence.
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02:44
Protecting Groups
Nucleophilic Substitution Reactions
Nucleophilic substitution reactions involve the replacement of a leaving group, such as a halogen, by a nucleophile. In the context of the given reaction, the bromine atom can be replaced by a nucleophile, such as a phenyl group, through an SN2 mechanism, which is a one-step process where the nucleophile attacks the electrophilic carbon, displacing the leaving group.
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Grignard Reagents
Grignard reagents are organomagnesium compounds used to form carbon-carbon bonds. They are typically prepared by reacting an alkyl or aryl halide with magnesium in an ether solvent. In the synthesis shown, a Grignard reagent could be used to introduce the phenyl group to the carbon chain, forming a new C-C bond and ultimately leading to the desired phenolic compound.
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Related Practice
Textbook Question
Suggest a synthetic scheme, involving a protecting group, to generate the molecule shown starting with the molecule at the left.
(d)
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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
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.
830
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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
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Textbook Question
In lieu of quenching the product of Grignard addition to a carbonyl with acid, alkyl halides can be added directly to generate ether products. Predict the product and show the mechanism of this process.
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