Figure 1. Diversity-oriented synthetic strategy with pyrimidine as a privileged structure.

(a) Pyrimidine-containing bioactive compounds. (b) 3D chemical space of pyrimidine and the comparison between pyrimidine-containing tricyclic 6/6/6 and 6/7/6 systems in terms of 3D diversity and complexity by overlaying energy-minimized conformers aligned along the pyrimidine substructure. (c) Synthetic strategy for diversity-oriented synthesis of pyrimidodiazepine- or pyrimidine-containing polyheterocycles through divergent pairing pathways.