Novel azalides derived from 16-membered macrolides. Part II: Isolation of the linear 9-formylcarboxylic acid and its sequential macrocyclization with an amino alcohol or an azidoamine.

The design and synthesis of novel 14- to 16-membered 11-azalides and 11-azalactams starting from 16-membered macrolides are described. Fifteen-substituted 16-membered azalides exhibited more potent antibacterial activities against resistant bacteria of Streptococcus pneumoniae.