Tutorial 2 alpha Carbonyl Chemistry MT2020 Memo PDF

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WEEK 2 TUTORIAL: CHEM320W - Organic Synthesis α-Carbonyl chemistry

2020

1. Draw the aldol reaction products from each compound.

2. What aldol product(s) is formed from each of the following compounds?

3. Which carbonyl compounds do not undergo an aldol reaction when treated with OH- in H2O?

4. How could you prepare the following compound using a starting material that contains no

more than three (3) carbons?

5. What unsaturated carbonyl compound is formed by dehydration of each β-hydroxy carbonyl compound?

6. Describe how the following compounds can be prepared using an aldol reaction in the first

step of the synthesis?

7. Propose a detailed mechanism for this acid catalyzed dehydration reaction of the β-hydroxy carbonyl.

8. What aldehyde or ketone is needed to prepare each of the following by aldol method?

9. 2-Pentylcinnamaldehyde, commonly called Flosal, is a perfume ingredient with a jasminelike odor. Flosal is an α,β-unsaturated aldehyde made by crossed aldol reaction between benzaldehyde and heptanal, followed by dehydration. Propose a detailed stepwise mechanism for the following reaction that prepares Flosal:

10. Draw products formed in each crossed aldol reaction:

11. Draw the products formed in each crossed aldol reaction of phenylacetaldehyde (C6H5CH2CHO) with each of the following: (a) CH2(CO2Et)2; (b) CH2(COCH3)2; (c) CH3COCH2CN

12. (i) What aldol product is formed when two molecules of butanal react together in the presence of a base? (ii) What reagents are needed product obtained in (i) to the following compounds?

13. Draw the products of the following reaction?

14. What keto-ester is formed when each ester is used in a Claisen reaction?

15. What crossed Claisen product is formed from each pair of compounds?

16. Avobenzone I a conjugated compound that absorbs UV light with wavelengths in the 320-400 nm region, so it is a common ingredient in commercial sunscreens. Write out two different crossed Claisen reactions that form Avebenzone:

17. What cyclic product is formed when each of the following 1,5-dicarbonyl compounds is treated with aqueous hydroxide?

18. Draw a detailed step-wise reaction mechanism for the conversion of 2,6-heptanedione to 3-methyl-2-cyclohexanone with NaOEt, EtOH:

19. Draw the products of each of the following reactions:

20. Two steps synthesis of analgesic ibuprofen include a carbonyl condensation reaction, followed by an alkylation reaction. Identify intermediates A and B in the synthesis of ibuprofen.

21. Draw the products formed when each dicarbonyl undergoes intramolecular aldol reaction followed by dehydration.

22. What starting materials are needed to synthesize each compound by a crossed Claisen reaction?

23. Fill in the missing reaction each of the following:

24. Draw the products when each pair of compounds is treated with hydroxide in water in a Robinson annulation reaction.

25. Show how each of the following compounds can be prepared from cyclohexanone:

26. Identify B-L in the following:

27. Challenging bonus problem: Write the steps needed to convert 1-methylcyclopentene to 20cyclohexanone (hint: Remember your CHEM220W alkene reactions)

28. Challenging bonus problem: Write the steps needed to convert 1-methylcyclopentene to 20cyclohexanone (hint: Remember your CHEM220W alkene reactions)...