Synthesis of a Conformationally Fixed Bicyclomarin Derivative

Based on an X-ray structure of cyclomarin bound to ClpC1, a new conformationally fixed, bicyclic cyclomarin derivative is synthesized in an effort to enhance antituberculosis activity. The synthesis of the linear heptapeptide and the two macrolactamizations proceed smoothly. Only the very last synthetic step, the cleavage of a benzyl ether, provides a low yield. Despite the successful synthesis, the resulting bicyclic compound shows reduced activity compared to cyclomarin.