We synthesized a series of oxazolidinone analogues bearing a N-hydroxyacetyl-substituted [1,2,5]triazepane or [1,2,5]oxadiazepane C-ring unit as homologues of an earlier drug candidate, eperezolid. Several of these compounds exhibited potent in vitro antibacterial activities towards not only Gram-positive, but also Gram-negative and linezolid-resistant pathogens. Compounds 21a and 21b, bearing a thiocarbamate side chain, showed high in vivo activity against methicillin-resistant Staphylococcus aureus SR3637, together with a promising safety profile in terms of weak inhibition of monoamine oxidase and cytochrome P450 isozymes.