Electrophilic reactivity and pi-complexation studies in 1,8-naphthylene-bridged [3.2]paracyclophane with a cyclobutane calliper

The 1,8-naphthylene-bridged [3.2]paracyclophane 1, a novel syn-paracyclopha ne which is further rigidified via a cyclobutane calliper, reacts with 2.2 equivalents of Br-2 in CCl4 in the dark to give the symmetrical dibromo der ivative 2. Bromination with excess Br-2 (6 equiv.) leads to further bromina tion at the 4-position of the naphthalene ring to give the tribromide 3. In contrast to [2.2]paracyclophane and naphthalene, compound 1 does not produ ce a persistent pi -complex with NO+. Reaction of 1 with AgOTf results in c ycloreversion to form a silver-complexed divinyl derivative 4 which could b e decomplexed with excess 18-crown-6 to form 5. With tetracobalt dodecacarb onyl a metal pi -complex on the exterior of the cyclophane unit was formed (6) with the cyclobutane ring remaining intact. NMR spectral features of th e resulting products are examined. AM1 minimizations were used as a guide t o structures and relative energies. The nitration, benzoylation, benzylatio n and ethylation of 1 were also studied.