Contributions to the Total Synthesis of Branimycin

The classical drugs used for the treatment of common bacterial diseases are often characterised by serious side effects and high-toxicity profiles. Additionally, in the last decade a rapid development of multidrug-resistant strains of bacterial pathogens has been observed. Consequently, there is an urgent need to discover new structural classes of antibacterial compounds, and to develop agents which are able to replace (or be associated with) the drugs which are currently in use. In 1998 researchers at the University of Göttingen isolated from a stem of Streptomyces a novel antibiotic, named branimycin. To access the complex structure of branimycin by total synthesis, the molecule was divided retrosynthetically into two fragments. Herein, 3 approaches are outlined to access the cis-octalin core fragment through substrate-controlled intramolecular (IMDA) or transannular (TADA) Diels-Alder reactions. Furthermore, the construction of the side-chain fragment in a convergent manner by the reaction of a differentially protected glyceraldehyde derivative with a chiral allenyl silane is described.