Abstract: AimTo synthesize oxazolindinone derivatives and test their antibacterial activities. Methods3-Halo-4-methylaniline was acylated with benzyl chloroformate, followed by cyclization with (R)-glycidyl butyrate, acylation with methanesulfonyl chloride, substitution with NaN₃, reduction with H₂+Pd/C or P(OMe)₃+HCl, acylation with Ac₂O, and bromination with NBS to form bromides VIIIa and VIIIb, Substitution of the bromides with various amines including aliphatic amine and aromatic amine provided the target compounds IXa and IXb. The in vitro antibacterial activity of the target compounds was tested. ResultsFifty one new compounds were designed and synthesized. And their structures were confirmed by ¹H NMR and elemental analyses or MS. Some physical constants such as ［α］²⁵_D were reported also. Compounds VIIb, IXa1, IXa2, IXa7, IXb1, IXb3, IXb10, IXb16 and IXb23 had moderate in vitro antibacterial activity against G⁺ bacteria but they were less active than linezolid or norfloxacin. ConclusionInsertion of methylene group between 4-position of phenyl and morpholinyl group in linezolid derivatives can not increase the antibacterial activity.