Synthesis of methano-bridged tetradehydro[36]annulene

Abstract

The title compound, 20,25-di-tert-butyl-21,22,23,24-tetradehydro-1,6-methano[36]annulene, was synthesized by the Wittig reaction of 1-(8-formylocta-1,3,5,7-tetraenyl)-6-(10-formyldeca1,3,5,7,9-pentaenyl)cyclohepta-1,3,5-triene with triphenyl(3-tert-butylpent-2-en-4-ynyl)phosphonium bromide, followed by intramolecular oxidative coupling of the resulting acyclic diacetylenic compound. ¹H NMR and electronic spectral data suggest that the [36]annulene is atropic.