Martin Fisher, [a,b] Ramkrishna Basak, [a,b] Arnout P. Kalverda, [b] Colin W. G. Fishwick, [a,b] W. Bruce Turnbull [a,b] and Adam Nelson* [a,b] , An approach for designing bioactive small molecules has been developed in which de novo structure-based ligand design (SBLD) was focused on regions of chemical space accessible using a diversity-oriented synthetic approach. The approach was exploited in the design and synthesis of a focused library of platensimycin analogues in which the com plex bridged ring system was replaced with a series of alternative ring systems. The affinity of the resulting compounds for the C163Q mutant of FabF was determined using a WaterLOGSY competition binding assay. Several compounds had significantly improved affinity for the protein relative to a reference ligand. The integration of synthetic accessibility with ligand design enabled focus to be placed on synthetically-accessible regions of chemical space that were relevant to the target protein under investigation.