Medium-Sized Cyclophanes. III. The Nitration Reaction of [2.2]Metacyclophane with Benzoyl Nitrate

The nitration reaction of [2.2]metacyclophane was carried out using dilute nitric acid or benzoyl nitrate under various conditions. Dilute nitric acid afforded 2-nitro-4, 5, 9, 10-tetrahydro-pyrene as the sole product, confirming Allinger’s original experiments, whereas benzoyl nitrate furnished a complex mixture consisting of 4, 5, 9, 10-tetrahydropyrene, 4, 5-dihydropyrene and pyrene, together with the nitration product. A series of experiments established that 4, 5, 9, 10-tetrahydropyrene, which was formed by the 1, 4-elimination reaction of Allinger’s intermediate, was the initial product of the reaction. Two competitive reactions, nitration and dehydrogenation reactions of the tetrahydropyrene, were assumed to be occurring, thus accounting for the experimental results.