Forster–Decker method

The Forster–Decker method is a series of chemical reactions that transform a primary amine (1) ultimately to a secondary amine (6).[1][2] The first step is the formation of a Schiff base (3), followed by alkylation, and hydrolysis.

The Forster-Decker method
The Forster-Decker method

Mechanism

1. The first step in the Forster-Decker Method is the formation of an imine (Schiff base) from a primary amine. [3]

  • Step A: Nucleophilic attack on the aldehyde by a primary amine
  • Step B: Proton Transfer - creating carbinolamine
  • Step C: Protonation of hydroxyl oxygen of carbinolamine
  • Step D: Formation of iminium ion by losing water molecule
  • Step E: Deprotonation giving imine product

2. The next step is alkylation of the imine product to form iminium ion.[4]

  • Step F: Alkylation of imine product with X-R' where X = Cl, Br or I

3. The final step is hydrolysis of the iminium ion to form a secondary amine and regenerate the aldehyde starting material. [5]

  • Step G: Nucleophilic attack by a water molecule
  • Step H: Proton transfers: shown in the mechanism using two molecules (water and acid) but this step might also be intramolecular
  • Step I: Reformation of carbonyl and kicking out the secondary amine
  • Step J: Deprotonation to regenerate aldehyde starting material

See also

References
  1. Forster, Martin Onslow (1899). "XCI.–Influence of substitution on specific rotation in the bornylamine series". Journal of the Chemical Society, Transactions. 75: 934–935. doi:10.1039/CT8997500934.
  2. Decker, H.; Becker, P. Ann. 1913, 395, 362.
  3. McMurry, John (1988). Organic Chemistry (Second ed.). Brooks/Cole Publishing Company. p. 674-675. ISBN 0-534-07968-7.
  4. "Forster-Decker Amine Synthesis". SynArchive.com The Organic Synthesis Archive. 2011–2022. Retrieved December 12, 2022.
  5. "Imine and Enamine Hydrolysis Mechanism". Chemistry Steps. 2016–2022. Retrieved December 13, 2022.


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