Interaction of (z)-4-bromo-1,3-di(2-thienyl)- 2-buten-1-one with amines, synthesis of di(2-thienyl)azolo[a]pyridines

Abstract

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.The continued interest in the azolo[a]pyridine system is due to the discovery of compounds in this class with a high level of biological activity and a broad range of action mechanisms [1-3]. The introduction of additional heterocyclic fragments into this system may lead to the appearance of new and useful properties of such compounds. Two common methods have been reported for hetaryl-substituted azolo[a]pyridines: 1) Condensation of 2,3-dialkylazolium salts with heterocyclic -diketones [4] and 2) Condensation of N-hetarylmethylpyridinium salt with isocyanates [5].In recent work [6, 7], we found a convenient method for the synthesis of diarylazolo[a]pyridinium salts, which involves the base-initiated cyclization of quaternary [(Z)-2,4-diaryl-4-oxo-2-butenyl]azolium salts obtained by the alkylation of 1,3-diazoles unsubstituted at the C-2 position using derivatives of 4-bromo-1,3-diphenyl-2-buten-1-one (-bromodypnone). In the present work, (Z)-4-bromo-1,3-di(2-thienyl)-2-buten-1-one (1) was used for the synthesis of azolo[1,2-a]pyridinium derivatives.