A central theme of organic synthesis is to provide well defined chemical space for the discovery of novel properties (e.g., for drug development). The chemical space can be accessed through either target-oriented synthesis (TOS) or diversity-oriented synthesis (DOS). TOS and DOS rely on efficient retro-and forward-synthetic planning, respectively, for achieving desired combination of molecular skeletons and appendages. In this regard, innovations in synthetic methodologies provide the key to the successful implementation of TOS and DOS.