Process for the Preparation of Oxazolidinone Derivatives

A process for the preparation of a compound of formula (I), or a salt thereof, both as the single (S) or (R) enantiomer, and as a mixture thereof,

• wherein R and R1, which can be the same or different, are hydrogen, CH3, CN, COOH or COOC1-C4 alkyl;
• R2 and R3, which can be the same or different, are hydrogen, F or Cl;
• and
• R4 is C1-C4 alkyl;
• which process comprises:
• a) the activation of the hydroxyl group in a compound of formula (II), or a salt thereof, as the single (S) or (R) enantiomer or as a mixture thereof, by means of a derivatization reagent to form a leaving group, and subsequent cyclization reaction in the presence of a catalyst or an azide compound;
• or
• b) the cyclization reaction of a compound of formula (II), or a salt thereof, as the single (S) or (R) enantiomer or as a mixture thereof, in presence of a strong base;
• wherein R5 is optionally substituted C1-C4 alkyl, aryl-C1-C4 alkyl or aryl;
• and R-R4 are as defined above;
• and,
• if desired, the resolution of a mixture of enantiomers of formula (I) to the single (S) or (R) enantiomer;
• and/or, if desired, the conversion of a compound of formula (I) to a salt thereof, or vice versa.