Interaction of azolo[a]pyridines

(Z)-4-Bromo-1,3-di(2-thienyl)-2-buten-1-one was obtained by the bromination of 1,3-di(2-thienyl)2-buten-1-one by NBS in anhydrous C[Cl.sub.4]. The starting butanone was obtained by the condensation of 1-(2-thienyl)-1-ethanone by the action of SO[Cl.sub.2]. The reaction of (Z)-4-bromo-1,3-di(2-thienyl)-2-buten-1-one with tertiary amines such as [Et.sub.3]N, pyridine, 1-alkyl-1,3-diazole, 1-alkylbenzimidazole, and 1-alkyl-1,2,4-triazole leads to quaternary salts. The azolium salts cyclize by the action of base to give di(2-thienyl)azolo[a]pyridinium derivatives. 3-Methyl-6,8-di(2-thienyl)[1,3]thiazolo[3,2-a]pyridin4-ium and 2,4-di(2-thienyl)pyrido[2,1-b]benzothiazol-10-ium bromides were obtained by the same procedure but without separating the intermediate quaternary salts. Keywords: 4-bromo-1,3-di(2-thienyl)-2-buten-1-one, imidazo[1,2-a]pyridine, pyrido[1,2-a]benzimidazole, pyrido[2,1-b]benzothiazole, [1,3 ]benzothiazolo[3,2-a]pyridine, [ 1,2,4]triazolo[4,3-a]pyridine.