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

10. Addition Reactions

Epoxide Reactions

Organic Chemistry

10. Addition Reactions

Epoxide Reactions

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5:09 minutes

Problem 10

Textbook Question

Working backward, design a synthesis of the following alcohol using two different epoxide/Grignard reagent combinations.

Verified step by step guidance

Step 1: Analyze the target alcohol structure. The molecule contains a secondary alcohol group (-OH) attached to a carbon that is connected to a cyclopropyl group and a chain ending in a tert-butyl group. This suggests that the alcohol was formed via nucleophilic attack on an epoxide followed by protonation.

Step 2: Identify possible epoxide precursors. The secondary alcohol could be formed by opening an epoxide at the position where the -OH group is located. Two potential epoxides are: (1) an epoxide with the cyclopropyl group and tert-butyl group already attached, or (2) an epoxide with the cyclopropyl group attached and a simpler alkyl chain that can be extended using a Grignard reagent.

Step 3: Select Grignard reagents for each pathway. For the first pathway, the Grignard reagent could be tert-butyl magnesium bromide (to introduce the tert-butyl group). For the second pathway, the Grignard reagent could be cyclopropyl magnesium bromide (to introduce the cyclopropyl group).

Step 4: Propose the synthesis for pathway 1. Use an epoxide with the cyclopropyl group and tert-butyl group already attached. React this epoxide with a Grignard reagent (e.g., tert-butyl magnesium bromide) to open the epoxide and form the secondary alcohol after protonation.

Step 5: Propose the synthesis for pathway 2. Use an epoxide with the cyclopropyl group attached and a simpler alkyl chain. React this epoxide with a Grignard reagent (e.g., cyclopropyl magnesium bromide) to open the epoxide and form the secondary alcohol after protonation. Extend the alkyl chain to include the tert-butyl group in subsequent steps.

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Key Concepts

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

Epoxide Chemistry

Epoxides are three-membered cyclic ethers that are highly reactive due to the strain in their ring structure. They can undergo nucleophilic ring-opening reactions, which are essential in organic synthesis. When reacted with Grignard reagents, epoxides can be transformed into alcohols, with the regioselectivity of the reaction depending on the substitution pattern of the epoxide.

Grignard Reagents

Grignard reagents are organomagnesium compounds that act as strong nucleophiles in organic reactions. They can react with electrophiles, including carbonyl compounds and epoxides, to form new carbon-carbon bonds. Understanding the reactivity and selectivity of Grignard reagents is crucial for designing synthetic pathways to alcohols from epoxides.

Synthesis Design

Synthesis design involves planning a series of chemical reactions to construct a target molecule from simpler starting materials. This process requires knowledge of reaction mechanisms, functional group transformations, and the ability to predict the outcomes of various reagent combinations. In this case, designing two different pathways to synthesize the same alcohol using epoxides and Grignard reagents illustrates the versatility of synthetic strategies in organic chemistry.

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Predict the product of the following epoxide addition reactions.

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In Chapter 13, we learned that epoxide opening can give different products, depending on whether the reaction occurs under acidic or basic conditions. Explain why the epoxide shown opens identically under either set of conditions.

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