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Synthesis of 2-Deoxy-2-halo-L-ascorbic Acids
1Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
The Journal of Organic Chemistry
|May 16, 1997
Summary
Researchers synthesized novel halogenated deoxy-L-ascorbic acids. Direct fluorination proved challenging, but an indirect method yielded 2-deoxy-2-fluoro-L-ascorbic acid efficiently.
Area of Science:
- Organic Chemistry
- Carbohydrate Chemistry
- Synthetic Chemistry
Background:
- 2-Deoxy-L-ascorbic acid is a vitamin C analog.
- Halogenated derivatives are important for chemical and biological studies.
- Previous synthetic routes for these compounds are limited.
Purpose of the Study:
- To develop facile synthetic methods for 2-halo-2-deoxy-L-ascorbic acids.
- To investigate direct and indirect halogenation strategies.
- To synthesize 2-deoxy-2-fluoro-L-ascorbic acid.
Main Methods:
- Direct halogenation of 2-deoxy-L-ascorbic acid using N-halosuccinimides (NIS, NBS, NCS).
- Direct fluorination using F-TEDA-BF(4).
- Indirect synthesis of 2-deoxy-2-fluoro-L-ascorbic acid via a bromo-fluoro intermediate and subsequent debromination.
Main Results:
- 2-Iodo- and 2-bromo-2-deoxy-L-ascorbic acids were synthesized efficiently.
- Chlorination produced the desired product along with a dichloro hemiketal.
- Direct fluorination yielded a difluoro hemiketal, while indirect fluorination followed by debromination provided 2-deoxy-2-fluoro-L-ascorbic acid in good yield.
Conclusions:
- Facile methods for synthesizing 2-iodo- and 2-bromo-2-deoxy-L-ascorbic acids were established.
- Direct fluorination is problematic, yielding undesired hemiketals.
- An effective indirect route for synthesizing 2-deoxy-2-fluoro-L-ascorbic acid was developed.