Claisen rearrangement

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The Claisen rearrangement is a powerful carbon-carbon bond-forming chemical reaction discovered by Rainer Ludwig Claisen. The heating of an allyl vinyl ether will initiate a [3,3]-sigmatropic rearrangement to give a γ,δ-unsaturated carbonyl.

Discovered in 1912, the Claisen rearrangement is the first recorded example of a [3,3]-sigmatropic rearrangement.

• Claisen, L.; Ber. 1912, 45, 3157.
• Claisen, L.; Tietze, E.; Ber. 1925, 58, 275.
• Claisen, L.; Tietze, E.; Ber. 1926, 59, 2344.

Contents 1 Mechanism 2 Variations 2.1 Aromatic Claisen rearrangement 2.2 Bellus-Claisen rearrangement 2.3 Eschenmoser-Claisen rearrangement 2.4 Ireland-Claisen rearrangement 2.5 Johnson-Claisen rearrangement 3 Hetero-Claisens 3.1 Aza-Claisen 3.2 Chromium Oxidation 3.3 Chen-Mapp Reaction 3.4 Overman rearrangement 3.5 Thio-Claisen 4 Claisen rearrangement in nature 5 General References 6 See also

[edit] Mechanism

The Claisen rearrangement (and its variants) are exothermic (about 84 kJ/mol), concerted pericyclic reactions which according to the Woodward-Hoffmann rules show a suprafacial reaction pathway.

There are substantial solvent effects in the Claisen reactions. More polar solvents tend to accelerate the reaction to a greater extent. Hydrogen-bonding solvents gave the highest rate constants. For example, ethanol/water solvent mixtures give rate constants 10-fold higher than sulfolane.^[1][2]

Trivalent organoaluminium reagents, such as trimethylaluminium, have been shown to accelerate this reaction.

1. Goering, H. L.; Jacobson, R. R.; J. Am. Chem. Soc. 1958, 80, 3277.
2. White, W. N.; Wolfarth, E. F.; J. Org. Chem. 1970, 35, 2196.

[edit] Variations

[edit] Aromatic Claisen rearrangement

The aromatic variation of the Claisen rearrangement is the [3,3]-sigmatropic rearrangement of an allyl phenyl ether to an intermediate which quickly tautomerizes to an ortho-substituted phenol.

[edit] Bellus-Claisen rearrangement

The Bellus-Claisen rearrangement is the reaction of allylic ethers, amines, and thioethers with ketenes to give γ,δ-unsaturated esters, amides, and thioesters.

• Malherbe, R.; Bellus, D.; Helv. Chim. Acta 1978, 61, 3096-3099.
• Malherbe, R.; Rist, G.; Bellus, D.; J. Org. Chem. 1983, 48, 860-869.
• Gonda, J.; Angew. Chem. Int. Ed. 2004, 43, 3516-3524.

[edit] Eschenmoser-Claisen rearrangement

The Eschenmoser-Claisen rearrangement proceeds from an allylic alcohol to a γ,δ-unsaturated amide, and was developed by Albert Eschenmoser in 1964.

• Wick, A. E.; Felix, D.; Steen, K.; Eschenmoser, A.; Helv. Chim. Acta 1964, 47, 2425-2429.
• Wick, A. E.; Felix, D.; Gschwend-Steen, K.; Eschenmoser, A.; Helv. Chim. Acta 1969, 52, 1030-1042.

[edit] Ireland-Claisen rearrangement

The Ireland-Claisen rearrangement is the reaction of an allylic acetate with strong base (such as butyl lithium) to give a γ,δ-unsaturated carboxylic acid.

• Ireland, R. E.; Mueller, R. H.; J. Am. Chem. Soc. 1972, 94, 5897-5898.
• Ireland, R. E.; Willard, A. K.; Tetrahedron Lett. 1975, 16, 3975-3978.

[edit] Johnson-Claisen rearrangement

The Johnson-Claisen rearrangement is the reaction of an allylic alcohol with trimethyl orthoacetate to give a γ,δ-unsaturated ester.

• Johnson, W. S. et al.; J. Am. Chem. Soc. 1970, 92, 741.

[edit] Hetero-Claisens

[edit] Aza-Claisen

• Kurth, M. J.; Decker, O. H. W.; J. Org. Chem. 1985, 50, 5769-5775.

[edit] Chromium Oxidation

Chromium can oxidize allylic alcohols to alpha-beta unsaturated ketones on the opposite side of the unsaturated bond from the alcohol. This is via a concerted hetero-claisen reaction, although there are mechanistic differences since the chromium atom has access to d- shell orbitals which allow the reaction under a less constrained set of geometries.

• Dauben, W. G.; Michno, D. M. J. Org. Chem., 1977, 42, 682.
• Organic Syntheses, Vol. 82, p.108 (2005). (Article)

[edit] Chen-Mapp Reaction

The Chen-Mapp reaction also known as the [3,3]-Phosphorimidate Rearrangement or Staudinger-Claisen Reaction installs a phosphite in the place of an alcohol and takes advantage of the Staudinger Ligation to convert this to an imine. The subsequent claisen is driven by the fact that a P=O double bond is more energetically favorable than a P=N double bond.

• Chen, B. Mapp, A K. J. Am. Chem. Soc. 2005, 127, 6712. Abstract

[edit] Overman rearrangement

The Overman rearrangement (named after Larry Overman) is a Claisen rearrangement of allylic trichloroacetimidates to allylic trichloroacetamides.

• Overman, L. E. J. Am. Chem. Soc. 1974, 96, 597.
• Overman, L. E. J. Am. Chem. Soc. 1976, 98, 2901.
• Overman, L. E. Accts. Chem. Res. 1980, 13, 218-224.
• Organic Syntheses, Coll. Vol. 6, p.507; Vol. 58, p.4 (Article)

[edit] Thio-Claisen

[edit] Claisen rearrangement in nature

The enzyme Chorismate mutase (EC 5.4.99.5) catalyzes the Claisen rearrangement of chorismate ion to prephenate ion, a key intermediate in the shikimic acid pathway (the biosynthetic pathway towards the synthesis of phenylalanine and tyrosine).

• Ganem, B. Angew. Chem. Int. Ed. Engl. 1996, 35, 936-945.

[edit] General References

• Rhoads, S. J.; Raulins, N. R.; Org. React. 1975, 22, 1-252.
• Ziegler, F. E.; Chem. Rev. 1988, 88, 1423-1452.
• Wipf, P.; Comp. Org. Syn. 1991, 5, 827-873.

[edit] See also

• Carroll rearrangement
• Cope rearrangement