Fürst-Plattner Rule

The Fürst-Plattner rule (also known as the trans-diaxial effect) describes the addition of nucleophiles to cyclohexene derivatives.

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Epoxidation of the substituted cyclohexene gives the product where the R group is in the pseudo-equatorial position. Nucleophilic opening of the epoxide can occur by attack at either the 1 or 2 position. The major product formed is from attack at the 1 position due to the instability of the twist boat product formed by addition at the 2 position (disfavored by approximately 5 kcal / mol). The Fürst-Plattner rule also applies to nucleophilic additions to imines and halonium ions.

A recent example of the Fürst-Plattner rule can be seen from Chrisman et al where limonene is epoxidized to give a 1:1 mixture of diastereomers. Exposure to a nitrogen nucleophile in water at reflux provides only one ring opened product in 75-85% ee.

References

• Fürst, A.; Plattner, P. A. Helv. Chim. Acta 1949, 32, 275.
• Kirby, A. J. Stereoelectronic Effects, New York: Oxford Science Publications, 2002. p. 54
• Chrisman, W.; Camara, J. N; Marcellini, K.; Singaram, B.; Goralski, C. T.; Hasha, D. L.; Rudolf, P. R.; Nicholson, L.W.; Borodychuck, K. K. Tetrahedron Lett. 2001, 42, 5805-5807.[1]