Fulvene mit inverser Ringpolarisation, 17 [1] Heptafulvene und Heptafulvenradikalkationen: Ringverengung durch Abspaltung eines C1-Fragments bei der Einelektronen-Oxidation von Bis(dimethylamino)dibenzoheptafulven
Abstract Disubstituted dibenzoheptafulvenes 4 are obtained from dibenzocycloheptene 8 via the carboxylic acid amide 10, and are characterized by spectroscopic methods and cyclic voltammetry. These dibenzoheptafulvenes are nonplanar, geometric enantiomorphy is shown by 1H-NMR of 12-dim ethyl-am ino-12-siloxydibenzoheptafulvene 4c. Oxidation o f 12,12-bis(dim ethylamino)dibenzo[a,d]-heptafulvene 4a with Ag(I), I2 or Cu(II) leads to the radical cation 7. In solution 7 is converted to dibenzocycloheptatriene and anthracene amidinium salts 18 and 19. The ratio o f these two amidinium salts depends on the reaction conditions. H-radical trapping from the medium is proposed for the formation of 18, while 19 must be formed under elimination of a C1-unit.
