Fürst-Plattner Rule

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



Epoxidation of the substitued 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.