Synthesis and activity of new macrolones: Conjugates between 6(7)-(2′-aminoethyl)-amino-1-cyclopropyl-3-carboxylic acid (2′-hydroxyethyl) amides and 4″-propenoyl-azithromycin

A set of novel macrolones containing the flexible C8 basic linker and quinolone 3-(2′-hydroxyethyl)carboxamido group has been prepared and structurally characterized by NMR and IR spectroscopy, mass spectrometry and molecular modeling. The new compounds were evaluated in vitro against a panel of erythromycin-susceptible and erythromycin-resistant Gram-positive and Gram-negative bacterial strains. Compared to azithromycin, most of the compounds exhibited improved in vitro potency against the key respiratory pathogens.