The Thiophene Analogue of Porphyrin: Tetrathiaporphyrin Dication

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.