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

26. Amines

Amines by Reduction

Organic Chemistry

26. Amines

Amines by Reduction

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2:05 minutes

Problem 63c,d

Textbook Question

Reductive amination of aldehydes and ketones is a versatile method for attaching alkyl groups to amines, but the alkyl group is restricted to a 1° or 2° carbon by this method. Prof. Phil Baran of Scripps Research Institute has reported (Science, 2015, 348 (6237), 886–891) a novel way to reduce an aromatic nitro group and add the resulting amine to an alkene so that the aromatic amine is bonded to a 3° carbon—all in a continuous sequence of reactions.
For example:

Predict the products using these starting materials, all of which are reported in this paper.
(c)
(d)

Verified step by step guidance

Step 1: Analyze the reaction conditions provided in the first image. The reaction involves the reduction of an aromatic nitro group to an amine using Fe³⁺ catalyst and PhSiH₃ in ethanol at 60°C, followed by alkylation of the resulting amine with an alkene in the presence of Zn and HCl(aq). This sequence allows the attachment of the amine to a tertiary carbon.

Step 2: For the second image, identify the starting materials: a nitrobenzene derivative (chloronitrobenzene) and an α,β-unsaturated ketone. The nitro group will be reduced to an amine, and the ketone will likely participate in a conjugate addition reaction with the amine, forming a new C-N bond.

Step 3: For the third image, identify the starting materials: a nitrobenzene derivative with a hydroxyl group and a cyano group, and an alkene. The nitro group will be reduced to an amine, and the alkene will likely undergo a hydroamination reaction, forming a new C-N bond at the tertiary carbon.

Step 4: Predict the intermediate steps for each reaction. In the first step, the nitro group is reduced to an amine. In the second step, the amine reacts with the alkene or α,β-unsaturated ketone to form a new bond at the tertiary carbon. Consider steric and electronic effects that may influence the reaction outcome.

Step 5: Consider the final products for each reaction. The first reaction produces an aromatic amine attached to a tertiary carbon. The second reaction likely forms a β-amino ketone. The third reaction forms an aromatic amine attached to a tertiary carbon, with the hydroxyl and cyano groups remaining intact.

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Key Concepts

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

Reductive Amination

Reductive amination is a chemical reaction that involves the conversion of an aldehyde or ketone into an amine through the formation of an imine intermediate, followed by reduction. This method is particularly useful for attaching alkyl groups to amines, but it is limited to primary and secondary carbon sources due to steric hindrance and reactivity considerations.

Nitro Group Reduction

The reduction of nitro groups to amines is a common transformation in organic chemistry, typically achieved using reducing agents such as hydrogen in the presence of a catalyst or chemical reductants like iron or tin. This reaction is significant because it allows for the conversion of aromatic compounds into more reactive amines, which can then participate in further reactions, such as the formation of carbon-carbon bonds.

Continuous Reaction Sequences

Continuous reaction sequences involve performing multiple chemical reactions in a single process without isolating intermediates. This approach enhances efficiency and can lead to higher yields of desired products. In the context of the question, it refers to the simultaneous reduction of a nitro group and the addition of the resulting amine to an alkene, allowing for the formation of a tertiary amine in a streamlined manner.

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