Birch Reduction

Definition:

Reduction of aromatic rings by means of alkali metals in liquid ammonia to give unconjugated dihydro derivatives:

Frequency of appearance:

        This bar graph represents all of the online articles that were found to contain this specific name reaction in the title of the article. Tetrahedron letters, Tetrahedron, Synthetic letters, Synthesis, Journal of Organic Chemistry and Journal of the American Chemical Society are represented here. This table by no means represents the periodicity of the name reaction found in the literature.

Original References:

1. Birch, A.J. Quart. Rev. (London), 4, 69 (1950).
2. Birch, A.J.; Smith, H. Quart. Rev. (London), 12, 17 (1958).

Recent academic references:     Click here for more references

3. Desymmetrization of Benzoic Acid in the Context of the Asymmetric Birch Reduction-Alkylation Protocol. Asymmetric Total Syntheses of (-)-Eburnamonine and (-)-Aspidospermidine

• Schultz, A.G.;* Pettus, L. J. Org. Chem, 62, 6855-6861 (1997).

4. Total Synthesis of (±)-Scopadulcic Acid B

• Overman, L.E.; et al., J. Am. Chem. Soc., 119, 12031-12040 (1997).

Recent process references:

5. Practical and Large-Scale Synthesis of rac-(3S,4aR,10aR)- 6-Methoxy-1-propyl-1,2,3,4,4a,5,10,10a-octahydrobenzo[g]quinoline-3-carboxylic Acid Methyl Ester

• Banziger, M.; Cercus, J.; Stampfer, W.; Sunay, U.;
  Org. Process Res. Dev.; 4(6); 460-466 (2000).  

Mechanism: http://www.arkat.org/arkat/journal/Named Reactions/Birch.htm

Scope and Limitations:

• Electron donating/ withdrawing leads to alpha/ beta unsaturated product. ^B
• Halogen, nitro, aldehyde and keto groups may be reduced. ^B
• Cosolvents may be needed for aromatics in liquid ammonia. ^B
• Iron salts may lower yields (Distilled ammonia is suggested). ^A
• Congugated olefins may react. Unconjugated do not. ^{A, B}

Synonyms: