Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

14. Synthetic Techniques

Retrosynthesis

Organic Chemistry

14. Synthetic Techniques

Retrosynthesis

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10:51 minutes

Problem 19

Textbook Question

Work backward to show how the cyclopropane would be synthesized from the chloroalkane shown.

Verified step by step guidance

Step 1: Identify the target molecule (cyclopropane derivative) and the starting material (benzyl chloride). The goal is to synthesize the cyclopropane ring from the chloroalkane through a series of reactions.

Step 2: Recognize that the formation of a cyclopropane ring typically involves a carbene or carbenoid intermediate. To generate this intermediate, the chloroalkane can undergo deprotonation to form a carbanion, followed by reaction with a reagent like CH2I2 (diiodomethane) in the presence of Zn/Cu to form the cyclopropane ring.

Step 3: Consider the stereochemistry of the target molecule. The (+/-) notation indicates the formation of a racemic mixture, meaning both enantiomers of the cyclopropane are formed. This suggests that the reaction mechanism does not favor one stereoisomer over the other.

Step 4: Plan the reaction sequence. First, treat the benzyl chloride with a strong base (e.g., NaOH or KOH) to form the benzyl carbanion. Next, react the carbanion with diiodomethane (CH2I2) in the presence of Zn/Cu to generate the cyclopropane ring.

Step 5: Verify the reaction conditions and intermediates. Ensure that the reagents used (base, CH2I2, Zn/Cu) are appropriate for the formation of the cyclopropane ring and that the stereochemistry aligns with the racemic mixture observed in the product.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Cyclopropane Synthesis

Cyclopropane can be synthesized through various methods, including the reaction of alkenes with reagents that facilitate cyclization. One common approach is the use of a chloroalkane, which can undergo nucleophilic substitution or elimination reactions to form the cyclopropane structure. Understanding the mechanisms of these reactions is crucial for determining the synthetic pathway.

Nucleophilic Substitution

Nucleophilic substitution is a fundamental reaction in organic chemistry where a nucleophile attacks an electrophilic carbon atom, replacing a leaving group. In the context of synthesizing cyclopropane from a chloroalkane, this process can involve the formation of a cyclic intermediate, which is essential for constructing the three-membered ring characteristic of cyclopropane.

Elimination Reactions

Elimination reactions involve the removal of atoms or groups from a molecule, resulting in the formation of a double bond or a ring structure. In synthesizing cyclopropane, elimination can occur from a chloroalkane to generate an alkene, which can then undergo further reactions to form the cyclopropane. Understanding the conditions and mechanisms of elimination is vital for successful synthesis.

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Related Practice

Textbook Question

Develop syntheses for the following compounds, using acetylene and compounds containing no more than four carbon atoms as your organic starting materials.

(a) 3-methylnon-4-yn-3-ol (“3-ol” means there is an OH group on C3.)

Textbook Question

Develop syntheses for the following compounds, using acetylene and compounds containing no more than four carbon atoms as your organic starting materials.

(b) cis-1-ethyl-2-methylcyclopropane

Textbook Question

Propose mechanisms to explain the opposite regiochemistry observed in the following two reactions.

Textbook Question

Show how you would accomplish the following synthetic conversions.

Textbook Question

For each of the following target molecules, design a multistep synthesis to show how it can be prepared from the given starting material:

Textbook Question

Identify A–E.

Textbook Question

Using cyclooctyne as your starting material, show how you would synthesize the following compounds. (Once you have shown how to synthesize a compound, you may use it as the starting material in any later parts of this problem.)

(h)

Textbook Question

For each of the following target molecules, design a multistep synthesis to show how it can be prepared from the given starting material:

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