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Tetraoxaporphyrinogen (Tetraoxaquaterene): Oxidation to the Tetraoxaporphyrin Dication
Author(s) -
Haas Wilhelm,
Knipp Bernd,
Sicken Martin,
Lex Johann,
Vogel Emanuel
Publication year - 1988
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.198804091
Subject(s) - dication , annulene , porphyrin , chemistry , yield (engineering) , nitric acid , formaldehyde , photochemistry , condensation , medicinal chemistry , organic chemistry , molecule , materials science , physics , metallurgy , thermodynamics
The well known, extremely reactive [18]annulene 1 and the hypothetical isomer 2 should be capable of being stabilized by CH 2 ‐ and CHCH‐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.