Synthesis of 6-(α-thienyl)azulene from 2-butoxy-4-(α-thienyl)-Δ5-dihydropyran

2,5-Dibutoxy-4-(α-thienyl)-Δ³-dihydropyran was obtained by bromoalkoxylation at the double bond and dehydrobromination of 2-butoxy-4-(α-thienyl)-Δ⁵-dihydropyran. Acid hydrolysis of the product in the presence of N-methylaniline hydrochloride gave a salt of 3-(α-thienyl)glutaconic dialdehyde dianil, treatment of which with cyclopentadienylsodium in alcohol gives the corresponding fulvene, which is thermally cleaved to N-methylaniline and 6-(α-thienyl)azulene.