Zur Kenntnis der Azulene, VI. Die Reaktion von Azulenen mit Onium‐Salzen

Abstract

Im Gegensatz zu den Substitutionsreaktionen des Benzols und seiner Homologen, bei denen Zwischenprodukte nur in seltenen Fallen bzw. unter extremen Bedingungen isoliert werden konnten3), sollten sowohl bei der elektrophilen als auch bei der

Nonbenzenoid aromatic systems. X. Formation, nuclear magnetic resonance spectral identification, and reactions of both Meisenheimer type and methyleneazulenate anions

“…while, with lithium dimethylamide (15), methyllithium (23), and sodium methylsulfinylmethide (27), products derived from nucleophilic addition to both the azulene ring 4 (predominant) and 6 positions are observed. The Meisenheimer type Of addition complexes formed with the amide nucleophiles (3 and 15) and azulene were shown to thermally equilibrate while those complexes resulting from ring addition by the carbon nucleophiles (18, 23, and 27) were thermally stable.…”

“…When equimolar amounts of tetrahydrofuran solutions of azulene and lithium dimethylamide (15) were mixed at -70°the solution color immediately turned to a light yellow. The nmr spectrum recorded at -20°was interpreted as showing the presence of lithium 4-iV, N-dimethylamino-4ff-azulenate ( 21) and lithium 6-N,N-dimethylamino- 6H-azulenate (22).…”

A Versatile and High‐Yield Route to Active and Well‐Defined Catalysts [Ru(bisphosphane)(H)(solvent) 3 ](BF 4 )

“…We thus sought a more general, simple, and high‐yielding synthesis. As reported by Chaudret and Tkatchenko et al,12 protonation of [Ru(1,2:5,6‐ η ‐cod)( η 6 ‐cot)] ( 6 )13 at low temperature by HBF 4 ⋅Et 2 O14 in CH 2 Cl 2 generates [Ru(H)(1,2:5,6‐ η ‐cod)( η 6 ‐cot)](BF 4 ) ( 7 ), which rearranges to [Ru(H)(1‐5‐ η ‐C 8 H$\rm{_{11}^{\prime }}$ 2 ](BF 4 ) (C 8 H$\rm{_{11}^{\prime }}$ =2,4‐cyclooctadienyl) upon warming. These authors further reported that addition of excess monodentate ligands (H 2 O, MeCN, MeP(Ph) 2 , ≥3 equivalents) to 7 at low temperature followed by warming to ambient temperature produces [Ru(1‐5‐ η ‐C 8 H$\rm{_{11}^{\prime })}$ (L) 3 ](BF 4 ) and 1,3‐cyclooctadiene (cod′) 12.…”

Synthesis of azulenic compounds with a homo- or hetero-atomic double bond at position 1

“…85 However, over a relatively short period a large number of couplings between azulene derivatives and various aryldiazonium salts had been performed (several examples are reviewed in Scheme 35). [86][87][88][89][90][91][92][93] All described couplings are regioselective occurring in 1(3) position of azulenes. Substitution with a second arylazo group at 3-position is not possible, except when starting from the electron rich 2-aminoazulene.…”