| abstract |
The present invention relates to a process for preparing a quinolone antibiotic intermediate having the formula:wherein R is C1-C2 alkyl, C1-C2 fluoroalkyl, C2-C4 alkenyl, methoxy, chloro, or bromo; R<1 >is a unit selected from the group consisting of C1-C2 alkyl, C2-C3 alkenyl, C3-C5 cycloalkyl, and phenyl, each of which can be substituted by one or more fluorine atoms; said process comprising the step of cyclizing an admixture of quinolone precursors, said admixture comprising a 2-ethoxy substituted intermediate having the formula:in the presence of a silylating agent. |