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

16. Conjugated Systems

Diels-Alder Retrosynthesis

Organic Chemistry

16. Conjugated Systems

Diels-Alder Retrosynthesis

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4:08 minutes

Problem 33a,b

Textbook Question

Show how Diels–Alder reactions might be used to synthesize the following compounds.
(a)
(b)

Verified step by step guidance

Step 1: Understand the Diels–Alder reaction mechanism. It is a [4+2] cycloaddition reaction between a conjugated diene and a dienophile, forming a six-membered ring. The reaction is stereospecific and regioselective, meaning the substituents on the diene and dienophile influence the stereochemistry and regiochemistry of the product.

Step 2: For compound (a), identify the diene and dienophile required to form the bicyclic structure. The bicyclic system suggests the use of a cyclic diene, such as cyclopentadiene, and a dienophile with bromine substituents. The bromine atoms on the dienophile will dictate the stereochemistry of the final product.

Step 3: For compound (b), identify the diene and dienophile required to form the six-membered ring with a cyano group. The cyano group suggests the dienophile should contain a nitrile (-CN) functional group. The diene could be a simple conjugated diene, such as 1,3-butadiene.

Step 4: Predict the stereochemistry and regiochemistry of the products. For compound (a), the bromine substituents on the dienophile will determine the stereochemistry of the bicyclic product. For compound (b), the cyano group will direct the regiochemistry of the addition, ensuring the nitrile group is positioned correctly on the six-membered ring.

Step 5: Draw the reaction schemes for both compounds. For (a), show the reaction between cyclopentadiene and a bromine-substituted dienophile. For (b), show the reaction between 1,3-butadiene and a nitrile-substituted dienophile. Ensure the stereochemistry and regiochemistry are consistent with the final products.

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Key Concepts

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

Diels–Alder Reaction

The Diels–Alder reaction is a [4+2] cycloaddition reaction between a conjugated diene and a dienophile, resulting in the formation of a six-membered ring. This reaction is a powerful tool in organic synthesis due to its ability to create complex cyclic structures with high stereoselectivity and regioselectivity. Understanding the mechanism, which involves the formation of a cyclic transition state, is crucial for predicting the products formed in the reaction.

Conjugated Dienes

Conjugated dienes are compounds that contain two double bonds separated by a single bond, allowing for delocalization of π electrons. This delocalization enhances the stability of the diene and makes it more reactive in Diels–Alder reactions. Recognizing the structure and reactivity of conjugated dienes is essential for designing synthetic pathways using this reaction.

Stereochemistry in Cycloaddition

Stereochemistry plays a significant role in Diels–Alder reactions, as the orientation of substituents on the diene and dienophile affects the stereochemical outcome of the product. The reaction can lead to the formation of stereoisomers, including cis and trans configurations, depending on the substituents' positions. Understanding how to predict and analyze these stereochemical outcomes is vital for synthesizing specific compounds.

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