Recent progress in the field of macrolide antibiotics

There continues to be a strong interest within the pharmaceutical industry in the use of macrolides as a starting point for the semisynthesis of novel antibacterial agents. The patenting activity in this area has been significant over the last 3 years. Many of the new patents involve ketolide derivatives, which contain a C-3 ketone modification. This is a direct consequence of the excellent activity against erythromycin-resistant organisms displayed by ketolide derivatives such as telithromycin and cethromycin. Other trends in recent macrolide research include modifications to the azalide scaffold of azithromycin and a renewed interest in 16-membered macrolides. These trends are reviewed by examining the new chemical series that have been revealed in the patent literature over the last 3 years.