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What stereoisomers are obtained from the following reactions?
b.
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Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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TOC.tableOfContents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding31
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds: Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
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Bruice 8th EditionCh. 7 - The Reactions of Alkynes • An Introduction to Multistep SynthesisProblema 57a
Bruice 8th EditionCh. 7 - The Reactions of Alkynes • An Introduction to Multistep SynthesisProblema 57aCapitolo 7, Problema 57a
Starting with ethyne, describe how the following compounds can be synthesized:
a. (3S,4R)-4-bromo-3-hexanol and (3R,4S)-4-bromo-3-hexanol
Guida verificata passo dopo passo1
Step 1: Begin with ethyne (C₂H₂) and perform a hydroboration-oxidation reaction to convert it into an aldehyde. This involves first reacting ethyne with disiamylborane (a bulky borane reagent) to form an organoborane intermediate, followed by oxidation with hydrogen peroxide (H₂O₂) in a basic solution (NaOH). This will yield acetaldehyde (CH₃CHO).
Step 2: Perform a Grignard reaction to extend the carbon chain. React acetaldehyde with ethylmagnesium bromide (C₂H₅MgBr) to form 3-pentanol. This reaction involves the nucleophilic attack of the Grignard reagent on the carbonyl carbon of acetaldehyde, followed by protonation during the acidic workup.
Step 3: Protect the hydroxyl group of 3-pentanol to prevent it from reacting in subsequent steps. Use a protecting group such as a silyl ether (e.g., TBDMSCl) in the presence of a base like imidazole to form the protected alcohol.
Step 4: Perform a bromination reaction to introduce a bromine atom at the 4-position. Use N-bromosuccinimide (NBS) in the presence of light or a radical initiator to selectively brominate the 4-position of the alkane chain. This step generates a racemic mixture of (3S,4R)-4-bromo-3-hexanol and (3R,4S)-4-bromo-3-hexanol.
Step 5: Deprotect the hydroxyl group to regenerate the free alcohol. Use a fluoride source such as tetrabutylammonium fluoride (TBAF) to remove the silyl protecting group, yielding the desired compounds: (3S,4R)-4-bromo-3-hexanol and (3R,4S)-4-bromo-3-hexanol.
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Alkyne Reactivity
Ethyne, or acetylene, is a simple alkyne that can undergo various reactions due to its triple bond. This reactivity allows for the formation of different functional groups through processes such as hydrogenation, halogenation, and nucleophilic addition. Understanding how alkynes react is crucial for synthesizing more complex molecules from simpler starting materials.
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Alkyne Hydration
Stereochemistry
Stereochemistry involves the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In the synthesis of (3S,4R)- and (3R,4S)-4-bromo-3-hexanol, it is essential to consider the stereochemical configuration at the chiral centers. This understanding helps in predicting the outcomes of reactions and the formation of specific isomers.
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Percorso guidato
1:38Polymer Stereochemistry Concept 1
Nucleophilic Substitution Reactions
Nucleophilic substitution reactions are fundamental in organic chemistry, where a nucleophile replaces a leaving group in a molecule. In the synthesis of the target alcohols, nucleophilic substitution can be employed to introduce the bromine atom at the desired position. Mastery of this concept is vital for constructing complex organic molecules from simpler precursors.
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01:47Nucleophiles and Electrophiles can react in Substitution Reactions.
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