Lewis Acid-Catalyzed Cyclotrimerization of Methyl 3-Acetylazulene-1-carboxylate in Alcohols

Abstract

An alcoholic solution of methyl 3-acetylazulene-1-carboxylate was treated with tetrachlorosilane, titanium(IV) chloride, thionyl chloride, and so on, at room temperature to give 1,3,5-tri(1-azulenyl)benzenes. It was found that thionyl chloride is useful for triple condensation. A dimeric intermediate, 1,3-bis(3-methoxycarbonyl-1-azulenyl)-2-buten-1-one, was also isolated. Its reaction with the starting monomer gave the trimeric 1,3,5-tri(1-azulenyl)benzene.

Keywords:

• Lewis acid
• Cyclotrimerization, Acetylazulene
• Triazulenylbenzene