The Dakin-West reaction is a chemical reaction that transforms an amino-acid into an amino-ketone using a carboxylic anhydride and a base, typically pyridine. Of special note, the amino-ketone product is always racemic.

With pyridine as a base and solvent, refluxing conditions are required. However, with the addition of 4-dimethylaminopyridine (DMAP) as a catalyst, the reaction can take place at room temperature.

With some acids, this reaction can take place even in the absence of an α-amino group.

This reaction should not be confused with the Dakin reaction.

Reaction mechanism

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The reaction mechanism involves the acylation and activation of the acid 1 to the mixed anhydride 3. The amide will serve as a nucleophile for the cyclization forming the azlactone 4. Deprotonation and acylation of the azlactone forms the key carbon-carbon bond. Subsequent ring-opening of 6 and decarboxylation give the final amino-ketone product.

References

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1. Dakin, H. D.; West, R. J. Biol. Chem. 1928, 78, 91.
2. Dakin, H. D.; West, R. J. Biol. Chem. 1928, 78, 745.
3. Dakin, H. D.; West, R. J. Biol. Chem. 1928, 78, 757.
4. Wiley, R. H.; Borum, O. H. Organic Syntheses, Coll. Vol. 4, p.5 (1963); Vol. 33, p.1 (1953). (Article)
5. Hoefle, G.; Steglich, W.; Vorbrueggen, H. Angew. Chem. Int. Ed. Engl. 1978, 17, 569.
6. Knorr, R.; Huisgen, R. Ber. 1970, 103, 2598.
7. Allinger, N. et al. J. Org. Chem. 1974, 39, 1730.

General References

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• Wiley, J. Org. Chem. 1947, 12, 43.
• Cornforth, J. W. Heterocyclic Compounds 1957, 5, 345.
• Buchanan, G. L. Chem. Soc. Rev. 1988, 17, 91-109.

Organic reactions