Goldberg reaction
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The Ullmann condensation or Ullmann ether synthesis is a variation of the Ullmann reaction, in which a phenol is coupled to an aryl halide to a diaryl ether in the presence of a copper compound, named after Fritz Ullmann.[1] The corresponding aniline or aryl amide reaction is sometimes called Goldberg reaction, named after Irma Goldberg.[2]


An example is the synthesis of p-nitrophenyl phenyl ether [3]

An active copper powder that is required for this reaction can be prepared by the reduction of copper sulfate by zinc metal in hot water causing the precipitation of elementary copper.

Goldberg reaction

An example of a Goldberg reaction is the synthesis of N-phenyl-anthranilic acid, an intermediate of acridone via the Goldberg reaction[4]

Synthesis of N-phenylanthranilic acid

An Ullmann-type aromatic amination reaction between an aryl iodide and an aryl amine as coupling partners has been published.[5] The catalyst used is formed from copper(I) iodide and phenanthroline. As this reaction proceeds well with an electron-rich aryl iodide it is a valuable alternative to the Buchwald-Hartwig amination reaction, which gives best yields with electron-poor aryl halides.

The scope is extended to amides [6][7][8] for example in the synthesis of this Camps cyclization precursor [9]:

Buchwald amidation reaction

References

  1. ^ Fritz Ullmann, Paul Sponagel (1905). "Ueber die Phenylirung von Phenolen". Berichte der deutschen chemischen Gesellschaft 38 (2): 2211–2212. doi:10.1002/cber.190503802176. 
  2. ^ Iram Goldberg (1906). "Ueber Phenylirungen bei Gegenwart von Kupfer als Katalysator". Berichte der deutschen chemischen Gesellschaft 39 (2): 1691–1692. doi:10.1002/cber.19060390298. 
  3. ^ Ray Q. Brewster and Theodore Groening, "Ether, p-nitrophenyl phenyl", Organic Syntheses, Coll. Vol. 2, p.445 Online article
  4. ^ C. F. H. Allen and G. H. W. McKee, "Acridone", Organic Syntheses, Coll. Vol. 2, p.15. (Online article)
  5. ^ H.B. Goodbrand, Nan-Xing Hu (1999). "Ligand-Accelerated Catalysis of the Ullmann Condensation: Application to Hole Conducting Triarylamines". Journal of Organic Chemistry 64: 670–674. doi:10.1021/jo981804o. 
  6. ^ Klapars, A.; Antilla, J. C.; Huang, X.; Buchwald, S. L. (2001). "A General and Efficient Copper Catalyst for the Amidation of Aryl Halides and the N-Arylation of Nitrogen Heterocycles". J. Am. Chem. Soc. (Communication) 123 (31): 7727–7729. doi:10.1021/ja016226z. 
  7. ^ Klapars, A.; Huang, X.; Buchwald, S. L. (2002). "A General and Efficient Copper Catalyst for the Amidation of Aryl Halides". J. Am. Chem. Soc. (Article) 124 (25): 7421–7428. doi:10.1021/ja0260465. 
  8. ^ Strieter, E. R.; Blackmond, D. G.; Buchwald, S. L. (2005). "The Role of Chelating Diamine Ligands in the Goldberg Reaction: A Kinetic Study on the Copper-Catalyzed Amidation of Aryl Iodides". J. Am. Chem. Soc. (Communication) 127 (12): 4120–4121. doi:10.1021/ja050120c. 
  9. ^ Jones, C. P.; Anderson, K. W.; Buchwald, S. L. (2007). "Sequential Cu-Catalyzed Amidation-Base-Mediated Camps Cyclization: A Two-Step Synthesis of 2-Aryl-4-quinolones from o-Halophenones". J. Org. Chem. 72 (21): 7968–7973. doi:10.1021/jo701384n. 
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