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

19. Reactions of Aromatics: EAS and Beyond

EAS:Retrosynthesis

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

EAS:Retrosynthesis

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4:24 minutes

Problem 47

Textbook Question

The following steps were used in the synthesis of the antimalarial thiaplakortone A. Identify the missing reagents, (a) and (b),

Verified step by step guidance

Examine the first transformation where the ether group is converted to an alcohol. This suggests a cleavage of the ether bond, likely through an acid-catalyzed hydrolysis. Consider using a strong acid like HCl or HBr as reagent (a) to facilitate this conversion.

In the second transformation, the alcohol group is oxidized to a ketone. This indicates the use of an oxidizing agent. Common oxidizing agents for such transformations include PCC (Pyridinium chlorochromate) or Jones reagent (CrO3, H2SO4). Choose an appropriate oxidizing agent for reagent (b).

The final step involves the addition of a sulfonamide group, followed by cyclization to form the thiaplakortone A structure. The sulfonamide reagent is likely a sulfonyl chloride, such as p-toluenesulfonyl chloride, which reacts with the amine group to form the sulfonamide linkage.

After the sulfonamide formation, the addition of H2SO4 suggests an acid-catalyzed cyclization or rearrangement to form the final thiaplakortone A structure. This step involves protonation and subsequent intramolecular reactions to achieve the desired ring closure.

Review the entire synthesis pathway to ensure that each reagent and condition aligns with the transformations observed in the chemical structures. Consider the functional groups present and the typical reactions they undergo to confirm the choice of reagents.

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Key Concepts

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

Reagents in Organic Synthesis

In organic chemistry, reagents are substances that are added to a reaction to cause a chemical change. Identifying the correct reagents is crucial for synthesizing a target compound, as they dictate the reaction pathway and the final product. Understanding the role of each reagent, including their reactivity and compatibility with other components, is essential for successful synthesis.

Reaction Mechanisms

A reaction mechanism describes the step-by-step process by which reactants are converted into products. It includes the formation and breaking of bonds, the intermediates formed, and the energy changes involved. Familiarity with common mechanisms, such as nucleophilic substitution or electrophilic addition, helps predict the outcomes of reactions and identify missing reagents in a synthesis.

Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. Recognizing functional groups is vital in organic synthesis, as they influence the reactivity and properties of compounds. Understanding how different functional groups interact can aid in determining the appropriate reagents needed for a specific transformation.

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