Elektronentransferreaktionen nichtalternierender chinoider und hydrochinoider Verbindungen Verhalten von 5,12‐Dimethoxynaphth[2,3‐a]azulen bei der Oxidation¹⁾

Abstract

Chirai 5,5',19,12'-tetramethoxy-l 1,ll'-binapbth-(2,3-a]azt~lcne (3a) is formed by oxidative coupling of Za with iron(l1l) chloride in dimethylfonnamide. The reaction of 2a with tropylium tetrafluoroborate (8), triphenylcarbenium salts 7, or trichlorwyclopropenylium tetrachloroaluminate (9) yields either biazulene 3a or electrophilic substitution at C-11, depending on the specific reaction conditions. In case of Za and 8 the azulenium lob, formed in the primary step, is transformed into 11 by reaction with triethylamine. Without base thc formation of biazulene 3r by a SET mechanism via radical cation 18 as intermediate is favored. 7 behaves similar, however, because of steric and electronic reasons an SE reaction could not be observed. Triazulenylcyclopropenylium perchlorate 12 is obtained by the reaction of 2a with 9. Structural details of the newly formed azulenes, biazulenes, and azulenium compounds are discussed with specific considerations of electrochemical and UV/VlS spectral propcrtics.Eigenschaften dieser Verbindungsklasse gehort und seine Ursache in der nichtalternierenden topologischen Struktur von 1 und 2 zu suchen ist, konnte ahnliches Verhalten bei Elektroneniibertragung im oxidativen Bereich erwartet werden. Der Hydrochinon-dimethylether 2a ist geeignet dies zu priifen. Die cyclovoltammetrischen Untersuchungen werden durch Diinnschicht-Spektroelektrochemie (thin layer spectroelectrochemistry) mit Hilfe optisch-transparenter Diinnschichtelektroden (OTTLE) erganzt. Damit wird die Strukturinterpretation der Zwischenstufen durch UV/VIS-Spektren ermoglicht. Praparative Umsetzungen erfolgen sowohl Chem.

Cyclopropenylium Cations, Cyclopropenones, and HeteroanaloguesRecent Advances

“…As an application of this method, the reaction of 1‚AlCl 4with 3 equiv of naphth[2,3-a]azulene 6 gave cation 7, having the longest-wavelength absorption at 592 nm, in 42% yield (eq 2). 10 A derivative of tris(2-thienyl)cyclopropenylium cation 9 was prepared in 37% yield by a similar reaction with thienylphenol 8 and was transformed into dianion 10 with a highly delocalized π-system, having the longest-wavelength absorption at 693 nm (eq 3). 11 This method is effective particularly for the reaction with activated π-systems.…”

“…As an application of this method, the reaction of 1 ·AlCl 4 - with 3 equiv of naphth[2,3- a ]azulene 6 gave cation 7 , having the longest-wavelength absorption at 592 nm, in 42% yield (eq 2) …”

Optoelectronic Molecular Switches Based on Dihydroazulene‐Vinylheptafulvene (DHA‐VHF)

“…The irreversible wave represents a two-step process involving a one-electron oxidation of the DHA subunit followed by a chemical step (EC-type mechanism) leading to a significant change in the molecular structure. Since polyenic radical cations have a preference for dimerization,' 34 ' it is reasonable to speculate on the formation of the dirneric dication species as shown in structure 41. The chemical reversibility of this EC-type process was confirmed by multisweep thin layer experiments.…”

10,10'-Dimethoxy-9,9'-biazuleno[2,1-c]phenanthrene

“…Hence, azulene possesses donor-acceptor characteristics that may be exploited in advanced functional electronic, optoelectronic, and electrochromic devices. Among azulene derivatives, expansion of the π-conjugated system of 1,1'-biazulene derivatives has attracted significant interest owing to their unique spectral and redox properties [1][2][3]. In that context, we recently reported that azulene-fused helicenes could be formed through 1-functionalized [5]helicenes by Pt(II)-catalyzed cycloisomerization [4,5].…”

“…Its crystal structure and electrochemical properties are also reported. 10,phenanthrene (2) 10-Methoxyazuleno[2,1-c]phenanthrene (1) was synthesized according to our previously reported method [3]. Under an argon atmosphere, a mixture of compound 1 (50 mg, 0.16 mmol) and APS (183 mg, 0.80 mmol) in degassed toluene (25 mL) was heated at 100 °C for 1 h. Additional APS (183 mg, 0.80 mmol) was added and the mixture was stirred for 2 h at 100 °C.…”