Synthesis of the elusive dibenzannelated dihydropyrene dibenzo[e,l]dimethyldihydropyrene, a molecular photo-switch

Article abstract of DOI:10.1016/0040-4039(96)01074-X

Synthesis of the unknown o-m-o-m-cyclophane derivative 13 is achieved by deoxygenation of the adduct 12, derived from a bis-Diels-Alder addition of furan to the intermediate bis-aryne generated by bis-dehydrobromination of dibromide 11. The colorless photochromic cyclophanediene 13 switches to the green dibenzannulene 14 on uv irradiation, and 14 thermally or photochemically reverse to 13, with E(act) = 20 kcal/mole.