Reaction of 1-azulenyl methyl sulfoxide (1) under acidic conditions gave the 1,1'-biazulene derivative 3. Methylmercapt groups of 3 were readily converted to formyl groups by Vilsmeier reaction to afford 3,3'-diformyl-l,1'-biazulene (4), which reacted with pyrrole in the presence of acetic acid to give the parent 1, 1'-biazulene (5). Reaction of 5 with pyridine in the presence of Tf2O gave 3,3'-dihydropyridyl- 1,1'-biazulene derivative 6. 3,3'-(4-Pyridyl)-1 1,1'-biazulene (7) was obtained by the reaction of 3 with KOH in EtOH at room temperature in good yield. (C) 2007 Elsevier Ltd. All rights reserved.
Synthesis and Redox Behavior of 1-Azulenyl Sulfides and Efficient Synthesis of 1,1′-Biazulenes
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-