Synthesis and photoreaction of polymethyl substituted [2.2]metaparacyclophanes

Polymethyl substituted [2.2]metaparacyclophanes were synthesized via the corresponding 2,11-dithia [3.3]metaparacyclophanes. Photooxygenation reaction of 4,5,6,12,13,15,16-heptamethyl[2.2]metaparacyclophane using a high pressure mercury lamp led to the mono-endoperoxidation of only the para benzene ring; this was attributed to the much larger degree of deformation of the para-benzene ring than of the meta-benzene ring. On the other hand, whilst irradiation of the photoreaction of 4,5,6,8,12,13,15,16-octamethyl[2.2]metaparacyclophane under the same reaction conditions produced only the bis-endoperoxide (on both the meta- and para-benzene rings).

► Polymethyl substituted [2.2]metaparacyclophanes were synthesized using sulphur analogues.
► Photooxygenation reaction of polymethyl[2.2]metaparacyclophanes afforded endoperoxide.
► Photooxygenation reaction is strongly affected by the bulkiness of the methyl group in the 8-position.