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

25. Condensation Chemistry

Robinson Annulation

Organic Chemistry

25. Condensation Chemistry

Robinson Annulation

Previous problemNext problem

1:42 minutes

Problem 59a

Textbook Question

Show how you would use Robinson annulations to synthesize the following compounds. Work backward, remembering that the cyclohexenone is the new ring and that the double bond of the cyclohexenone is formed by the aldol with dehydration. Take apart the double bond, then see what structures the Michael donor and acceptor must have.
(a)

Verified step by step guidance

Step 1: Analyze the target molecule. The compound contains a cyclohexenone ring with a methyl group at the β-position relative to the carbonyl group. This suggests that the Robinson annulation was used to form the cyclohexenone ring.

Step 2: Work backward by breaking the double bond in the cyclohexenone ring. The double bond is formed during the aldol condensation step with dehydration. Identify the precursor structures that would undergo aldol condensation.

Step 3: Determine the Michael donor and acceptor. The Michael donor is typically an enolate, and the Michael acceptor is an α,β-unsaturated carbonyl compound. In this case, the methyl group at the β-position suggests that the Michael donor was a methyl ketone.

Step 4: Propose the starting materials. The Michael donor is acetone (CH3COCH3), and the Michael acceptor is methyl vinyl ketone (CH2=CHCOCH3). These two compounds undergo a Michael addition followed by an aldol condensation to form the cyclohexenone ring.

Step 5: Outline the reaction sequence. First, the enolate of acetone attacks the β-carbon of methyl vinyl ketone in a Michael addition. This intermediate then undergoes an intramolecular aldol condensation, followed by dehydration, to form the cyclohexenone ring with the methyl group at the β-position.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

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

Robinson Annulation

The Robinson annulation is a key reaction in organic synthesis that combines a Michael addition and an aldol condensation to form cyclic compounds. It typically involves the reaction of a ketone or aldehyde with a Michael donor, followed by dehydration to create a double bond. This method is particularly useful for constructing complex ring structures, such as cyclohexenones, which are often found in natural products.

Aldol Condensation

Aldol condensation is a fundamental reaction in organic chemistry where aldehydes or ketones react in the presence of a base to form β-hydroxy carbonyl compounds. This reaction involves the formation of an enolate ion, which then attacks another carbonyl compound. The resulting β-hydroxy carbonyl can undergo dehydration to yield an α,β-unsaturated carbonyl compound, which is crucial in the formation of double bonds in cyclic structures.

Michael Addition

The Michael addition is a nucleophilic addition reaction where a nucleophile adds to an α,β-unsaturated carbonyl compound. In this reaction, the nucleophile typically attacks the β-carbon, leading to the formation of a new carbon-carbon bond. This step is essential in the Robinson annulation process, as it sets the stage for the subsequent aldol condensation and the formation of the desired cyclic structure.

Watch next

Master Robinson Annulation with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

Predict the product of the following reactions.

(b)

442

views

Textbook Question

Show how the following molecule might be synthesized using the Robinson annulation.

441

views

Textbook Question

Propose mechanisms for the following reactions.

(d)

431

views

Textbook Question

The base-catalyzed reaction of an aldehyde (having no α hydrogens) with an anhydride is called the Perkin condensation. Propose a mechanism for the following example of the Perkin condensation. (Sodium acetate serves as the base.)

435

views

Textbook Question

Show how you would use Robinson annulations to synthesize the following compounds. Work backward, remembering that the cyclohexenone is the new ring and that the double bond of the cyclohexenone is formed by the aldol with dehydration. Take apart the double bond, then see what structures the Michael donor and acceptor must have.

(b)

417

views

Multiple Choice

Provide the product for the following Robinson Annulation Reaction.

How would you prepare the following compound using a Robinson annulation reaction between a di-ketone and an alpha, beta unsaturated ketone?

789