The novel transition metal free synthesis of 1,1′-biazulene
摘要:
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.