BROMINATION OF EXO-TRICYCLO[3.2.1.0(2,4)]OCTANE AND ENDO-TRICYCLO[3.2.1.0(2,4)]OCTANE

Reaction of exo-tricyclo[3.2.1.0(2,4)]octane with bromine in CCl4 or methanol proceeds, at least in part, by way of a classical ion to give 1,3-addition products. Electrophilic attack by bromine occurs with inversion at the corner to the C2C4 bond and nucleophilic attack by both inversion and retention. In methanol the initial cation species is sufficiently short lived that it does not relax to the classical cation, and nucleophilic attack with inversion competes with skeletal rearrangement. Reaction of endo-tricyclo[3.2. 1.0(2,4)]octane with bromine in CCl4 gives 1,3-addition and an addition rearrangement product which are formed with inversion at the site of both electrophile and nucleophile attack. A further dibromide product is observed, the formation of which is suppressed in methanol. In methanol nucleophilic attack occurs with inversion to give a mixture of 1,3-addition and rearrangement products.