title: Substituted penicillin and cephalosporin derivatives. I. Stereospecific introduction of the C-6(7) methoxy group.
mesh_terms: D002511:Cephalosporins / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D008722:Methods; D008745:Methylation; D010406:Penicillins / Q000138:chemical synthesis*
chemical_list: D002511:Cephalosporins; D010406:Penicillins