Aromatic Tetraepoxyannulenes: Tetraepoxy[26]annulenes(4.2.2.2) and Tetraepoxy[30]annulenes(4.4.4.2) – Systems with High Molecular Dynamics The twofold cyclizing Wittig reaction of the bis-aldehyde 6 with the ylide of the bis-phosphonium salt 7 yields tetraepoxy[26]annulene(4.2.2.2) 4, which exists in the two isomeric forms 4a (EE,Z,E,Z) and 4b (EE,Z,E,E). Annulene 4a is a highly dynamic system down to −80°
The synthesis of diepoxy[16]annulene(6.2) 3 is described. The dialdehyde (E,E)-3,3′-([2,2′-bifuran]-5,5′-diyl)bis[2-propenal] 4 undergoes an intramolecular as well as an intermolecular as well as an intermolecular McMurry coupling to give the diepoxy[16]annulene 3 beside the tetraepoxy[32]annulene(6.2.6.2) (5). According to the spectroscopic data 3 has the Z,Z,E,Z-configuration and it turns out to