A convenient synthesis of the antibacterial agent linezolid

Starting with 3,4-difluorobenzoic acid (8) and (S)-epichlorohydrin (13) a convergent synthesis of linezolid (1) was developed that is attractive for large scale preparation of the drug. The synthetic strategy involves a 1+3 cycloaddition reaction between the chiral epoxide 11 (prepared from 13) and isocyanate 3 (obtained from 8) that was generated in situ by a Curtius rearrangement. The resulting Schiff base precursor of linezolid (12) crystallized from the reaction mixture and was readily converted to linezolid by an acid-catalyzed hydrolysis followed by an acetylation.