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-1, 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 ...
