high yields into 1-azulenyl methyl and phenyl sulfides and 1,3-bis(methyl- and phenylthio)azulenes through treatment with diethylamine is also described. Reaction of the 1-azulenylsulfides with MCPBA afforded 1-azulenyl sulfoxides, which were then efficiently transformed into 1,1′-biazulene derivatives under acidic conditions. The redox properties of 1-azulenyl methyl and phenyl sulfides, 1,3-bis(methyl-
Nickel-catalyzed coupling of bromides of 1,6-methano[10]annulene and azulene. A facile synthesis of biannulene and bi-, ter-, quater-, and polyazulenes
作者:Masahiko Iyoda、Koichi Sato、Masaji Oda
DOI:10.1016/s0040-4039(00)89262-x
日期:1985.1
The active nickel complex generated in situ by reduction of NiBr2(PPh3)2 with zinc in the presence of Et4NI is a useful reagent for the dehalogenativecoupling of 2-bromo-1,6- methano[10]annulene and 1-bromo- and 1,3-dibromoazulenes.
Syntheses of polycyclic compounds by oxidative coupling of azulene-1-azoarenes
作者:Alexandru C. Razus
DOI:10.1039/a907402c
日期:——
The chemical oxidation of azulene-1-azoarenes with FeCl3 in benzene was studied. For unsubstituted azo compounds, a 4′,4′ coupling takes place yielding biarylic derivatives 4 or 6. 4′-Substituted azulene-1-azobenzenes react depending on the nature of the substituent. Electron-withdrawing substituents such as NO2 increase the oxidation potential of the starting azo compounds and, as a consequence, they hinder the oxidative coupling. On the contrary, electron-releasing substituents such as 4′-methoxy (compound 1b) activate the position 3 in the azulene moiety and coupling in this position takes place as the main pathway; products with three and four azulene moieties coupled in the 1 and 3 positions (11 and 12) were also separated and characterized. The coupling product for the oxidation of compound 1c with a 4′-CH3 substituent results in 15% yield only; large amounts of oligomers and polymers with substituted methyl detected in the reaction mixture prove that in 1c the benzylic position is also a reactive one. A mechanism with a radical cation intermediate generated by the single-electron transfer oxidation of the starting azo compounds is proposed.
An efficientsynthesis of 1-heteroaryl- and 1,3-bis(heteroaryl)azulenes was established by electrophilic substitution. The reaction of azulenes and 1,1'-biazulene with the triflate of N-containing heteroarenes proceeded smoothly in the presence of excess heteroarenes to afford the corresponding 1-dihydroheteroaryl- and 1,3-bis(dihydroheteroaryl)azulene derivatives in good yields. The 1-dihydroheteroaryl-