Robust strategies to rapidly access compound libraries featuring high levels of structural complexity,skeletal diversity and drug-likeness for drug discovery remain in urgent demand.We propose a highly efficient and modular strategy to create such libraries.As an illustration,we performed privileged-substructure-based diversity-oriented synthesis of a collection of 50 heterocyclic compounds comprising 10 distinctive scaffolds.The strategy essentially utilizes a sequence of Ugi four-component reactions incorporating the indole substructure and microwave-assisted cyclizations via branched pathways.Cheminformatic analysis of the three-dimensional molecular shape using principal momeent of inertia analysis indicated that the library covers regions of chemical space complementary to libraries populated by compounds from traditional combinatorial chemistry or commercial vendors.Moreover,drug-likeness analysis suggested that this library of compounds also exhibits high drug-likeness with desirable pharmacokinetic and safety profiles.