Composition Standard-grade<unk>  is primarily composed of four related compounds known as<unk> s A, B, C, and D. Each of these compounds can be present in varying amounts and can differ by lot.<unk>  A has been found to have the most antibacterial activity, followed by<unk>  B.<unk> s C and D are about half as active as<unk>  A. Some of these related compounds have been purified and can be studied and researched individually. Synthesis Over the three decades after the discovery of<unk>  A and its activity as an antimicrobial, many attempts were made to synthesize it in the laboratory. The presence of 10 stereogenic carbons and several points of distinct substitution has made the total synthesis of<unk>  A a formidable task. Complete syntheses of<unk> s’ related structures and precursors such as 6-deoxyerythronolide B have been accomplished, giving way to possible syntheses of different<unk> s and other macrolide antimicrobials. Woodward successfully completed the synthesis of<unk>  A.<unk>  related compounds * Azithromycin * Carbomycin * Cethromycin * Clarithromycin * Dirithromycin * Mitemcinal * Oleandomycin * Roxithromycin * Spiramycin * Telithromycin * Tylosin
Erythromycin
Cethromycin
Methicillin
Ampicillin
Meropenem
Clarithromycin
Natamycin
Cefotaxime