Abstract
Natural products and natural product derived compounds are popular sources of new drugs and thus also play a pivotal role in the discovery and development of new antibiotics. The antibiotic fidaxomicin possesses promising antibacterial activity against several Gram-positive bacteria, though the poor bioavailability due to low water solubility, highly limits its clinical application. This thesis deals with our efforts to semisynthetically modify the macrocyclic antibiotic fidaxomicin (1) and presents our approaches starting from the isolation of this complex natural product from its natural source, the actinobacteria Actinoplanes deccanensis.