Synthesis and Antibacterial Activity of 3-(Morpholinopyridyl)-5-substituted Isoxazole Derivatives

A series of 3-(morpholinopyridyl)-5-substituted isoxazole derivatives were prepared starting from 6-chloropyridine-3-carbaldehyde. The structures of the products were confirmed by IR, NMR and MS data. The products have an isoxazole mother core with 3-morpholinopyridyl substitution and possess an approximately planar structure. In addition a number of ester groups, amino groups, triazole groups and oxazolidinone groups were introduced to 5-position of the isoxazole mother core. The antibacterial activities of the products against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Staphylococcus epidermis, Enterococcus faecalis and Escherichia coli were studied. Inferior activities (MIC>32 mg/L) were observed in comparison with linezolid. The results imply that the lack of 5-sp(3) hybridization structure may result in the decrease of antibacterial activity of isoxazole derivatives.