The present invention relates to novel phenyl oxazolidinone compounds of formula I, their pharmaceutically acceptable analogs, tautomeric forms, stereoisomers, polymorphs, prodrugs, metabolites, salts or solvates thereof. The invention also relates to the processes for the synthesis of novel compounds of formula I or their pharmaceutically acceptable analogs, tautomeric forms, stereoisomers, polymorphs, prodrugs, metabolites, salts or solvates thereof. The present invention also provides pharmaceutical compositions comprising novel compounds of formula I and methods of using them. The compounds of the present invention are useful as antimicrobial agents, effective against a number of aerobic and/or anaerobic Gram positive and/or Gram negative pathogens such as multi drug resistant species of Staphylococcus, Streptococcus, Enterococcus, Bacterioides, Clostridia, H. influenza, Moraxella, acid-fast organisms such as Mycobacterium tuberculosis as well as Linezolid resistant species of Staphylococcus and Enterococcus.