Wagner–Meerwein rearrangement

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A Wagner–Meerwein rearrangement is a class of carbocation 1,2-rearrangement reactions in which a hydrogen, alkyl or aryl group migrates from one carbon to a neighboring carbon.[1][2]

Several reviews have been published.[3][4][5][6][7]

The rearrangement was first discovered in bicyclic terpenes for example the conversion of isoborneol to camphene:[8]

Dehydration of Isoborneol to Camphene

The story of the rearrangement reveals that many scientists were puzzled with this and related reactions and its close relationship to the discovery of carbocations as intermediates.[9]

In a simple demonstration reaction of 1,4-dimethoxybenzene with either 2-methyl-2-butanol or 3-methyl-2-butanol in sulfuric acid and acetic acid yields the same disubstituted product,[10] the latter via a hydride shift of the cationic intermediate:

Carbocation rearrangement Polito 2010

Currently, there are works relating to the use of skeletal rearrangement in the synthesis of bridged azaheterocycles. These data are summarized in [11]

Some examples of Wagner-Meerwein rearrangement in heterocyclic series

Plausible mechanisms of the Wagner–Meerwein rearrangement of diepoxyisoindoles:

Plausible mechanisms of the Wagner-Meerwein rearrangement of diepoxyisoindoles

The related Nametkin rearrangement named after Sergey Namyotkin involves the rearrangement of methyl groups in certain terpenes. In some cases the reaction type is also called a retropinacol rearrangement (see Pinacol rearrangement).

See also[edit]

References[edit]

  1. ^ Wagner, G. (1899). J. Russ. Phys. Chem. Soc. 31: 690. 
  2. ^ Hans Meerwein (1914). "Über den Reaktionsmechanismus der Umwandlung von Borneol in Camphen; [Dritte Mitteilung über Pinakolinumlagerungen.]". Justus Liebig's Annalen der Chemie 405 (2): 129–175. doi:10.1002/jlac.19144050202. 
  3. ^ Popp, F. D.; McEwen, W. E. (1958). "Polyphosphoric Acids As a Reagent in Organic Chemistry". Chem. Rev. 58 (2): 375. doi:10.1021/cr50020a004. 
  4. ^ Cargill, R. L. et al. (1974). "Acid-catalyzed rearrangements of β,γ-unsaturated ketones". Accts. Chem. Res. 7 (4): 106–113. doi:10.1021/ar50076a002. 
  5. ^ Olah, G. A. (1976). "Stable carbocations, 189. The σ-bridged 2-norbornyl cation and its significance to chemistry". Accts. Chem. Res. 9 (2): 41. doi:10.1021/ar50098a001. 
  6. ^ Hogeveen, H.; Van Krutchten, E. M. G. A. (1979). "Wagner-meerwein rearrangements in long-lived polymethyl substituted bicyclo[3.2.0]heptadienyl cations". Top. Curr. Chem. Topics in Current Chemistry 80: 89–124. doi:10.1007/BFb0050203. ISBN 3-540-09309-5. 
  7. ^ Hanson, J. R. (1991). "Wagner–Meerwein Rearrangements". Comp. Org. Syn. 3: 705–719. doi:10.1016/B978-0-08-052349-1.00077-9. ISBN 978-0-08-052349-1. 
  8. ^ March, Jerry (1985), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (3rd ed.), New York: Wiley, ISBN 0-471-85472-7 
  9. ^ Birladeanu, L. (2000). "The Story of the Wagner-Meerwein Rearrangement". J. Chem. Ed. 77 (7): 858–863. doi:10.1021/ed077p858. 
  10. ^ Polito, Victoria; Hamann, Christian S.; Rhile, Ian J. (2010). "Carbocation Rearrangement in an Electrophilic Aromatic Substitution Discovery Laboratory". Journal of Chemical Education 87 (9): 969. doi:10.1021/ed9000238. 
  11. ^ Zubkov, F. I. ; Zaytsev, V. P.; Nikitina, E. V.; Khrustalev, V. N.; Gozun, S. V.; Boltukhina, E. V.; Varlamov, A. V. (2011). "Skeletal Wagner–Meerwein rearrangement of perhydro-3a,6;4,5-diepoxyisoindoles". Tetrahedron 67 (47): 9148. doi:10.1016/j.tet.2011.09.099.