Patent / 1998
One-pot preparation of azithromycin
Hovione Inter Ltd.
In prepg. azithromycin from erythromycin A by forming its oxime, Beckmann rearrangement of the oxime into the imino ether, redn. of the imino ether to 9-deoxo-9a-aza-9a-homo-erythromycin and reductive methylation of the latter, the last 2 steps are carried out in 1-pot sequentially, using a noble metal (Rh, Pt, Pd, Ru) catalyst and H in the presence of HCHO or a HCHO source, e.g., paraformaldehyde, in AcOH as solvent.