Cadiot–Chodkiewicz coupling

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The Cadiot–Chodkiewicz coupling in organic chemistry is a coupling reaction between a terminal alkyne and a haloalkyne catalyzed by a copper(I) salt such as copper(I) bromide and an amine base.[1][2] The reaction product is a di-acetylene or di-alkyne.

Cadiot-Chodkiewicz coupling overview

The reaction mechanism involves deprotonation by base of the acetylenic proton followed by formation of a copper(I) acetylide. A cycle of oxidative addition and reductive elimination on the copper center then creates a new carbon-carbon bond.

Related couplings are the Glaser coupling and the Eglinton coupling.

Cadiot–Chodkiewicz coupling[edit]

In one study[3] the Cadiot–Chodkiewicz coupling has been applied in the synthesis of acetylene macrocycles starting from cis-1,4-diethynyl-1,4-dimethoxycyclohexa-2,5-diene. This compound is also the starting material for the dibromide through NBS and silver nitrate:

Cadiot–Chodkiewicz coupling application

The coupling reaction itself takes place in methanol with piperidine, the hydrochloric acid salt of hydroxylamine and copper(I) bromide.

Eglinton reaction[edit]

In the related Eglinton reaction[4] two terminal alkynes are coupled directly by a copper(II) salt such as cupric acetate.

Eglinton Reaction 1.jpg

The Eglinton Reaction[5] has been used to synthesize a number of fungal antibiotics and is important for carbon-carbon bond formation via the oxidative coupling of alkynes.[6]

Eglinton Reaction Mechanism 1.jpg

This procedure was used in the synthesis of cyclooctadecanonaene.[7] Another example is the synthesis of diphenyldiacetylene from phenylacetylene.[8]

Hay coupling[edit]

The Hay coupling (1962) is another version of the Glaser coupling with the TMEDA complex of copper(I) chloride.[9] An example is the coupling of trimethylsilylacetylene.[10]

See Also[edit]

References[edit]

  1. ^ Chodkiewicz, W. Ann. Chim. Paris 1957, 2, 819–69.
  2. ^ Cadiot, P.; Chodkiewicz, W. In Chemistry of Acetylenes; Viehe, H. G., Ed.; Marcel Dekker: New York, 1969; pp 597–647.
  3. ^ Bandyopadhyay, Arkasish; Varghese, Babu; Sankararaman, Sethuraman. "Synthesis of 1,4-Cyclohexadiene-Based Acetylenic Macrocycles with Cadiot−Chodkiewicz Coupling. Structure of a Tub-Shaped Tetrameric Container". The Journal of Organic Chemistry 71 (12): 4544–4548. doi:10.1021/jo0605290. 
  4. ^ G. Eglinton and A. R. Galbraith, J. Chem. Soc., 889 (1959).
  5. ^ Eglinton, G.; Galbraith, A. R.; Chem. Ind. 1956, 737.
  6. ^ Eglinton, G.; McRae, W. Adv. Org. Chem. 1963, 4, 225.
  7. ^ K. Stöckel and F. Sondheimer (1988), "[18]Annulene", Org. Synth. ; Coll. Vol. 6: 68 
  8. ^ I. D. Campbell and G. Eglinton (1973), "Diphenyldiacetylene", Org. Synth. ; Coll. Vol. 5: 517 
  9. ^ Hay, Allan S. "Oxidative Coupling of Acetylenes. II". The Journal of Organic Chemistry 27 (9): 3320–3321. doi:10.1021/jo01056a511. 
  10. ^ Graham E. Jones, David A. Kendrick, and Andrew B. Holmes (1993), "1,4-Bis(trimethylsilyl)buta-1,3-diyne", Org. Synth. ; Coll. Vol. 8: 63