The synthesis of (9S)-9-alkyl-9-hydroxyerythromycin A derivatives and their ketolides

A short, concise synthesis of a novel series of (9S)-9-alkyl-9-hydroxyerythromycin A derivatives and their corresponding ketolides, is described. The key chemical transformation is a stereoselective addition of organomagnesium or organolithium agents to the 9-position of the suitably protected macrolide templates 8 and 13.