Furfuryl alcohol can be transformed in a simple way into the long‐awaited sulfur analog of porphyrin, the tetrathiaporphyrin dication 1, isolated as the perchlorate. The key to the synthesis is a remarkably straightforward sulfur/oxygen exchange in tetraoxaporphyrinogen. As would be expected from the relatively large van der Waals radius of sulfur, the transformation from the tetraoxaporphyrin dication to 1 is accompanied by loss of planarity in the ring system.

The well known, extremely reactive [18]annulene 1 and the hypothetical isomer 2 should be capable of being stabilized by CH2‐ and CHCH‐groups as internal and external bridges, respectively. The corresponding hydrocarbons, 3 and 4, are still unknown, although they are of great interest as links between the non‐natural annulenes and the porphyrin 5 or the porphycene 6 recently synthesized for the first time. It has now been possible to prepare the tetraoxa analogues of 5 and 6, i.e. the dications 7 and 8. In both cases they could be isolated as the perchlorates and structurally characterized, revealing their relationship with 5 and 6, respectively. In the synthesis of 7 the decisive step was a MacDonald condensation, followed directly by an oxidation, whereas the route to 8 led via a McMurry coupling and subsequent oxidation. Reaction of 2,2′‐difurylmethane with formaldehyde afforded tetraoxaporphyrinogen in low yield, which could be oxidized with nitric acid to the tetraoxaporphyrin.

hand der charakteristischcn roten Fluorcszeni (hci Anregung mit Licht der Wellcnlinge 366 nm) des Dikations 4 leicht lokalisiert wcrden.[ 101 Die (vorllufig)

ZUSCHRIFTENAutoren, die e k e ,,Zuschrift" veroffentlichen wollen, soliten vor der Abfassung ihres Manuskripts unbedingt die ,,Hinweise f i r Autoren" lesen, die jeweils im Januarheft eines Jahrgangs nach dem Inhaltsverzeichnis gedruckt sind; auf Anforderung konnen sie auch von der Redaktion erhalten werden.

The well known, extremely reactive [18]annulene 1 and the hypothetical isomer 2 should be capable of being stabilized by CH2‐ and CHCH‐groups as internal and external bridges, respectively. The corresponding hydrocarbons, 3 and 4, are still unknown, although they are of great interest as links between the non‐natural annulenes and the porphyrin 5 or the porphycene 6 recently synthesized for the first time. It has now been possible to prepare the tetraoxa analogues of 5 and 6, i.e. the dications 7 and 8. In both cases they could be isolated as the perchlorates and structurally characterized, revealing their relationship with 5 and 6, respectively. In the synthesis of 7 the decisive step was a MacDonald condensation, followed directly by an oxidation, whereas the route to 8 led via a McMurry coupling and subsequent oxidation. Reaction of 2,2′‐difurylmethane with formaldehyde afforded tetraoxaporphyrinogen in low yield, which could be oxidized with nitric acid to the tetraoxaporphyrin.