A simple method for deprotection of the N- and O-carbobenzoxy groups and N-methylation of the desosamine sugar moiety of ketolides. Application to the synthesis of ketolide analogues with various 9-iminoether moieties and their antibacterial activities.

A simple synthetic method for deprotection of the N- and O-carbobenzoxy groups (Cbz) of the desosamine sugar moiety of ketolides is reported. This deprotection method is applicable to the synthesis of a variety of ketolide analogues with various 9-iminoether moieties in good to moderate yield. Among the ketolide derivatives prepared by this method, compound 7g with a quinoline-6-yl moiety showed potent activity against erythromycin-resistant pathogens as well as Haemophilus influenzae.