Über zweistufige Redoxsysteme, VIII¹⁾ Synthese heterocyclisch tetrasubstituierter Äthylene und ihrer höheren Oxidationsstufen

Abstract

ZielsetzungVon Systemen der allgemeinen Struktur 1 ist zu erwarten, daB sie in drei Oxidationsstufen auftreten, die reversibel ineinander ubergehen. Sie konnen einen erheblichen Anteil an Radikalkationen enthalten4.5), der sich uber die Semichinonbildungskonstante K messen laBt6).

Organic Electron Donors as Powerful Single‐Electron Reducing Agents in Organic Synthesis

“…In the early 1970s, the first TAFs [112] were already being studied in regard to their electronic properties and were described as two-step reversible redox systems. [7] Nonetheless, .…”

Synthesis of diselenadiazafulvalenes and influence of steric strain on their anodic behavior

“…The yellow solution was dried over Na 2 SO 4 and the solvent was evaporated. The yellow powder was then recrystallized from EtOH and gave title compound 5 as yellow needles, R f (CH 2 Cl 2 ) 0.79; mp 142 ЊC (lit., 8 142 ЊC); 1 H NMR δ 8.55-8.39 (1H, dd, 3 J = 8.3 Hz, 4 J = 1.5 Hz), 8.31-8.13 (1H, dd, 3 J = 8.1 Hz, 4 J = 1 Hz), 7.86-7.71 (1H, td, 3 J = 8.1 Hz, 4 J = 1.5 Hz), 7.70-7.54 (1H, td, 3 J = 8.3 Hz, 4 J = 1 Hz); 13…”

“…Upon cooling, bis(o-nitrophenyl) diselenide 6 precipitated. Filtration afforded 24.20 g of compound 6 as yellow plates (71%, calculated on starting o-nitroaniline), mp 215 ЊC (lit., 8 209 ЊC); R f (CH 2 Cl 2 ) 0.84; 1 H NMR δ 8.42-8.24 (2H, dd, 3 J = 8.1 Hz, 4 J = 1.5 Hz), 7.94-7.78 (2H, dd, 3 J = 7.6 Hz, 4 J = 1.6 Hz), 7.57-7.28 (4H, m); 13…”

“…Evaporation of the solvent afforded a dark orange oil, which was distilled twice. (Kugelrohr, 0.04 mbar, ‡ 115 ЊC) to give 5.45 g (93%) of compound 8 as a yellow oil, R f (CH 2 Cl 2 ) 0.70; 1 H NMR δ 7.94-7.80 (1H, dd, 3 J = 8.1 Hz, 4 J = 1.3 Hz), 7.78-7.66 (1H, dd, 3 J = 7.8 Hz, 4 J = 1.3 Hz), 7.45-7.29 (1H, td, 3 J = 7.3 Hz, 4 J = 1.3 Hz), 7.22-7.09 (1H, td, 3 J = 7.3 Hz, 4 J = 1.3 Hz), 2.71 (3H, s); 13…”

Partial and Complete Reduction of Heterocycles Containing More than One Heteroatom

“…This product, however, undergoes spontaneous oxidation back to the dihydropyrazine (97), which is also produced by direct reduction of the parent pyrazine with sodium dithionate. 37 The stability of the 1,4-tetrapyrazine system is utilized in a synthesis of chiral alcohols (99) via the reduction of the corresponding bis-diamides (98) with lithium triethylborohy- As early as 1891 Claisen noted that isoxazoles, when treated with sodium and either pentyl alcohol or moist diethyl ether, undergo reductive ring opening to give 1,3-enaminoketones. 39 These products may then be hydrolyzed to 1,3-dicarbonyl compounds.…”