Earlier semi-synthetic studies of erythromycin A culminated in the discover
y of two successful second generation macrolide antibiotics, azithromycin a
nd clarithromycin, for the treatment of community-acquired bacterial infect
ions. More recent structural modifications of erythromycin A have resulted
in the discovery of novel ketolide antibiotics and new motilide prokinetic
agents. This review is an account of the semi-synthetic developments from e
rythromycin A by chemical transformations.