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

Abstract

The 1,8-naphthylene-bridged [3.2]paracyclophane 1, a novel syn-paracyclophane which is further rigidified via a cyclobutane calliper, reacts with 2.2 equivalents of Br₂ in CCl₄ in the dark to give the symmetrical dibromo derivative 2. Bromination with excess Br₂ (6 equiv.) leads to further bromination 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 produce a persistent π-complex with NO⁺. Reaction of 1 with AgOTf results in cycloreversion to form a silver-complexed divinyl derivative 4 which could be decomplexed with excess 18-crown-6 to form 5. With tetracobalt dodecacarbonyl a metal π-complex on the exterior of the cyclophane unit was formed (6) with the cyclobutane ring remaining intact. NMR spectral features of the resulting products are examined. AM1 minimizations were used as a guide to structures and relative energies. The nitration, benzoylation, benzylation and ethylation of 1 were also studied.