Identification of 4-aryl-1H-pyrrole[2,3-b]pyridine derivatives for the development of new B-Raf inhibitors.

During the last years, a significant interest in the identification of new classes of B-Raf inhibitors has emerged. In this study, which was conceived within an effort that culminated in the recent report of the first dual inhibitors of B-Raf and Hsp90, we describe the identification of four compounds based on 4-aryl-1H-pyrrole[2,3-b]pyridine scaffold as interesting starting points for the development of new B-Raf inhibitors. Structure-activity relationships and predicted binding modes are discussed. Moreover, the novelty of the newly identified structures with respect to currently known B-Raf inhibitors was assessed through a ligand-based dissimilarity assessment. Finally, structural modifications with the potential ability to improve the activity toward B-Raf are put forward.