CHEM 332

Problem Set 4 Key

1. Predict the major products of the following reactions; indicate proper stereochemistry when necessary

2. When optically active (S)-2-methylcyclopentanone is treated with aqueous base, the compound losses its optical activity. Explain this observation and draw a mechanism that shows the racemization.

3. Give a complete arrow-pushing mechanism for the following reactions.

4. Draw the correct arrows for the indicated mechanism and show the correct final product.

5. Explain which is the stronger Brønsted acid by drawing the appropriate conjugate bases and any resonance contributors.

6. Rank the following in order of increasing Bronsted acidity, briefly explain using drawings of the conjugate base anions as appropriate.

7. Synthesize the target structure on the right from the starting structure on the left. Provide the reagents, conditions, and intermediate molecules at each step. Do not show any mechanisms.

8. In the scheme below; determine the structures of the intermediate compounds.

9. Propose an efficient synthesis for each of the following compounds using the malonic ester synthesis.

10. Propose an efficient synthesis for each of the following compounds using the acetoacetic ester synthesis.

11. Identify the reagents necessary to accomplish each of the following transformation.

12. What carboxylic acid and alcohol are needed to prepare the following ester by Fischer esterification?

13. What starting materials are needed to prepare the compound by the Michael reaction?

14. What starting material(s) are needed to synthesize the compound using an aldol reaction.

15. What starting material(s) are needed to synthesize the compound by a Claisen reaction?

16. What starting material(s) are needed to synthesize the compound by a Michael reaction?

17. Amides are synthesized by reacting an amine with a acid chloride. In this reaction the amine is the nucleophile. Rank the three amines in order of increasing rate of reaction with an acid chloride.

18. Even though B contains three ester groups, a single Dieckmann product results when B is treated with NaOCH3 in CH3OH, followed by H3O+ . Draw the structure and explain why is the only product formed.