Mechanism of the rearrangement of the bicyclo [4.2. 0] octan system to the bicyclo [3.2. 1] octan system

A concerted mechanism has been demonstrated for the rearrangement of a tetracyclic ion including a bicyclo [4.2.0] octan system to hibaol, using a selective deuteration on the migrating bond. The stereochemistry of the selectively introduced deuterium was determined by three routes: 1. comparison of the high field 1H NMR spectra of the deuterated and undeuterated compounds, using double irradiation; 2. high field 1H NMR, coupled with molecular mechanics calculations; 3. two dimensional homo and heteronuclear NMR.