Focused enumeration and assessing the structural diversity of scaffold libraries: conformationally restricted bicyclic secondary diamines.

Comprehensive enumeration of conformationally restricted bicyclic secondary diamines (CRDA) was performed within defined structural limits, yielding a library of all theoretically possible compounds of this class, potentially useful as building blocks for drug design. In order to assess structural diversity of the generated library, molecular geometries of the library members were optimized using DFT calculations. It was shown that the distance between the amino groups and their relative orientation in space vary widely over the whole library, which might be beneficial for diversity-oriented conformational restriction approach in drug discovery. There are many representatives of "three-dimensional" scaffolds in the CRDA library. Selected literature data on biological activity of the known CRDA derivatives were discussed, demonstrating utility of the CRDA scaffold hopping in drug design.