Design, Synthesis, and Antibacterial Evaluation of Oxazolidinones with Fused Heterocyclic C-Ring Substructure.

A series of novel oxazolidinone antibacterials with diverse fused heteroaryl C-rings bearing hydrogen bond donor and hydrogen bond acceptor functionalities were designed and synthesized. The compound with benzoxazinone C-ring substructure (8c) exhibited superior activity compared to linezolid against a panel of Gram-positive and Gram-negative bacteria. Structural modifications at C5-side chain of 8c resulted in identification of several potent compounds (12a, 12b, 12g, and 12h). Selected compounds 8c and 12a showed very good microsomal stability and no CYP450 liability, thus clearing preliminary safety hurdles. A docking model of 12a binding to 23S rRNA suggested that the increased potency of 12a is due to additional ligand-receptor interaction.