What Is Barton Nitrite Photolysis?
In 1960, Barton first reported that nitrites generate δ-nitroso alcohols under light, which can be further derived into δ-hydroxy oximes. Barton nitrite photolysis is a powerful tool for C-H bond functionalization, providing a direct and effective way to synthesize a variety of valuable compounds.
The Barton reaction has good regioselectivity for the cleavage of C-H bonds, that is, it selectively occurs on the C-H bond at the 5th position of the oxygen-free radical. Because this reaction can achieve functionalization on inactive C-H, it is often used in organic synthesis, such as the synthesis of complex steroid structures.
- Reactants: Alkyl nitrites.
- Products: δ-Hydroxy oximes.
- Reaction type: Oxidation reaction.
- Related reaction: Hoffmann-Loffler-Freytag reaction.
Fig 1. Barton nitrite photolysis reaction and its mechanism. [1]
Mechanism of Barton Nitrite Photolysis
This reaction is a free radical mechanism. First, under light, the RO-NO bond undergoes homolytic cleavage to generate oxygen radicals and nitroxide radicals. Then the free radical undergoes 1,5-hydrogen migration from C to O to generate carbon radicals. The carbon radical and nitroxide radical combine to form the final product.
Application Examples of Barton Nitrite Photolysis
- Example 1: In the process of synthesizing β-isocupreidine (β-ICD) from quinoline, the Barton reaction is used as a key step. [2]
- Example 2: In recent years, the application of Barton nitrite photolysis reaction in continuous flow photochemistry has been further developed. By optimizing the reactor design and light source configuration, the synthesis of products at the gram level or even the kilogram level has been achieved. In addition, this reaction has also been used to develop the synthesis of new polymer coatings and other materials. [3]
Fig 2. Synthetic examples via Barton nitrite photolysis reaction.
Related Products
| CAS No. | Structure | Product | Inquiry |
| 10489-74-4 |  | Ethyl aminohydroxyiminoacetate | Inquiry |
| 3849-21-6 |  | Ethyl cyano(hydroxyimino)acetate | Inquiry |
| 7431-25-6 |  | 3-Hydroxy-3-methyl-2-butanone oxime | Inquiry |
| 849833-56-3 |  | (1Z)-N'-Hydroxy-2-methylpropanimidamide | Inquiry |
References
- Jie Jack Li. Name Reactions-A Collection of Detailed Mechanisms and Synthetic Applications, Fourth Edition, 2014, 30-31.
- Nakano A, et al. Advanced Synthesis & Catalysis, 2005, 347(14), 1790-1796.
- Dario Cambié, et al. Chem. Rev. 2016, 116(17), 10276–10341.
