Photochemical generation of benzene-naphthalene biplanemers

A direct biplanemer synthesis could be achieved by a quantitative [4 pi+4 pi]photocycloaddition of benzyloxy substituted benzene and naphthalene rings (3d,e reversible arrow 4d,e). Since the products do not show a thermal Cope rearrangernent-in contrast to the related longicyclic conjugated 9,10-benzotricyclo[4.2. 2.2(2.5)]docleca-3,7,9-trienes- but a quantitative reverse reaction, they are interesting systems for an optical switching. (c) 2005 Elsevier Ltd. All rights reserved.