Design, synthesis and antimicrobial activity of heteroannulated chromeno[3′,2′:5,6]pyrido[2,3-d][1,3]thiazolo[3,2-a]pyrimidines

Abstract

The current research is directed to construct a novel category of linear annulated chromeno[3`,2`:5,6]pyrido[2,3-d][1,3]thiazolo[3,2-a]pyrimidines. The chemical reactivity of the recently synthesized aldehyde 1 was examined toward a diversity cyclic methylene ketones, cyclic enamines and cyclic enols. Friedländer condensation of aldehyde 1 with 1,3-cyclohexanediones gave the multi-linear chromenopyrido- pyrimidothiazoloquinolines 2 and 3. Also, treating aldehyde 1 with some pyrazolones furnished annulated chromenopyridopyrazolopyridothiazolopyrimidines 4-6. Further, 1,3-thiazolidine-2,4-dione and barbituric acid condensed with aldehyde 1 giving chromenopyridothiazolopyridothiazolopyrimidine 7 and chromenopyridopyrimido-thiazolopyridopyrimidine 8, respectively. Moreover, reacting aldehyde 1 with cyclic enamines (6-amino-2-thiouracil and 6-amino-1,3-dimethyluracil) and cyclic enols (4-hydroxycoumarin and 1-ethyl-4-hydroxyquinolin-2(1H)-one) furnished polyfused heterocycles 9-12, respectively. During in vitro investigation of the antimicrobial efficiency, the synthesized compounds showed considerable activity against yeast and fungal strains, as well as moderate to high activity against Gram-positive and Gram-negative bacteria. Polyfused compounds 4-6 showed significant efficiency against all types of tested microorganisms.

Graphical Abstract

Keywords:

• Friedländer
• heteroannulation
• active methylene nucleophiles
• cyclic enols
• cyclic enamines

Declaration of interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.