Robinson annulation

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The Robinson annulation is a chemical reaction used to create a six-membered ring α,β-unsaturated ketone using a ketone (or aldehyde) and methyl vinyl ketone.^[1][2][3] It is named after the British chemist who discovered it, Sir Robert Robinson while at the University of Oxford.

In addition to methyl vinyl ketone, 1-chloro-3-propanone^[4][5] and isoxazoles^[6] will give the same product.

Proline has been used to resolve the entantiomeric isomers of Robinson annulations.^[7]

Contents 1 Reaction mechanism 2 Variations 2.1 Wichterle reaction 3 References 4 See also

[edit] Reaction mechanism

Methyl vinyl ketone (or variants thereof) are essential for the Robinson annulation as they are simultaneously a Michael acceptor and able to take part in an aldol condensation. The first step in the Robinson annulation is a Michael addition followed by an aldol reaction as the annulation step in the process. The reaction then proceeds as an aldol condensation to make the desired cyclohexenone ring.

[edit] Variations

[edit] Wichterle reaction

The Wichterle reaction is a variant of the Robinson annulation that replaces methyl vinyl ketone with 1,3-dichloro-cis-2-butene.^[8][9]

[edit] References

1. ↑  Rapson, W. S.; Robinson, R.; J. Chem. Soc. 1935, 1285.
2. ↑  Bergmann, E. D.; Gingberg, D.; Pappo, R. Org. React. 1959, 10, 179. (Review)
3. ↑  Gawley, R. E. Synthesis 1976, 777-794. (Review)
4. ↑  Heathcock, C. H.; Ellis, J. E.; McMurry, J. E.; Coppolino, A. Tetrahedron Lett. 1971, 12, 4995.
5. ↑  Heathcock, C. H.; Mahaim, C.; Schlecht, M. F.; Utawanit, T. J. Org. Chem. 1984, 49, 3264. (DOI:10.1021/jo00192a004)
6. ↑  McMurry, J. E. Organic Syntheses, Coll. Vol. 6, p.781 (1988); Vol. 53, p.70 (1973). (Article)
7. ↑  Organic Syntheses, Coll. Vol. 7, p.368 (1990); Vol. 63, p.37 (1985). (Article)
8. ↑  Wichterle, O. et al. Coll. Czech. Chem. Commun. 1948, 13, 300.
9. ↑  Kobayashi, M.; Matsumoto, T. Chem. Lett. 1973, 957.
10. Organic Syntheses, Coll. Vol. 5, p.869 (1973); Vol. 45, p.80 (1965). (Article)

[edit] See also

• Michael reaction
• The Wieland-Miescher ketone is the Robinson annulation product of 2-methyl-1,3-cyclohexanedione and methyl vinyl ketone