Fragment-based drug discovery (FBDD) has become an efficient methodology toward the identification of small-molecule leads.The majority of commercially available fragment libraries are predominantly populated with flat (hetero)aromatic chemotypes. On the other hand, nature is three-dimensional and therefore recognizes small molecules in a complementary 3D-fashion, and so drugs are likely to be more selective for their targets if they are three-dimensional too.

Compounds with diverse and well-developed 3D-shapes have become the most attractive ones on the market of screening compounds for HTS for the last several years. Fsp3 parameter has become one of the most important criterion of HTS libraries value since it was introduced in 2009 by Frank Lovering et.al as a measure of three-dimensionality and therefore complexity for libraries members.

Scaffold/molecule saturation may benefit:
¬ More diversity;
¬ More complexity;
¬ Access to greater chemical space;
¬ Improved phys-chem parameters (logP; PSA; water solubility etc.);
¬ More opportunity to reduce scaffold MW;
¬ More opportunity for further scaffold modification;
¬ Natural product-likeness;
¬ Better affinity to target proteins and greater selectivity;
¬ Easy access to IP-clean field.