Synthesis of designed new 1,3,4-oxadiazole functionalized pyrano [2,3-f] chromene derivatives and their antimicrobial activities.

Diethyl 2-(((4-methyl-2-oxo-2H-chromen-7-yl)oxy)methylene)malonate was synthesized from coumarin 1 and diethyl ethoxymethylene malonate in ethanol, followed by cyclization in diphenyl ether to give chromene-9-carboxylate . Sugar hydrazones were formed by reacting hydrazide with D-galactose, D-mannose, and D-xylose, then acetylated to per--acetyl derivatives . Heating with acetic anhydride at 100 °C gave oxadiazolines . Compound , obtained by refluxing with carbon disulfide, was alkylated to or reacted to give . Further reactions yielded acetoxy derivative and hydroxy derivative . Compounds and were synthesized using thiomorpholinophenyl ureido/thioureido-s-triazine. These compounds were characterized and evaluated for antibacterial activity against Gram (+ve) bacteria (, ) and Gram (-ve) bacteria (, ) in addition to yeast-like fungi (). Compounds , , , , , and showed the highest antibacterial activity. Molecular docking was performed to study their binding with transpeptidases.