BRAF inhibitors based on an imidazo[4,5]pyridin-2-one scaffold and a meta substituted middle ring

We recently reported on the development of a novel series of BRAF inhibitors based on a tripartite A-B-C system characterized by a para-substituted central aromatic core connected to an imidazo[4,5]pyridin-2-one scaffold and a substituted urea linker. Here, we present a new series of BRAF inhibitors in which the central phenyl ring connects to the hinge binder and substrate pocket of BRAF with a meta-substitution pattern. The optimization of this new scaffold led to the development of lownanomolar inhibitors that permits the use of a wider range of linkers and terminal C rings while enhancing the selectivity for the BRAF enzyme in comparison to the para series. \ua9 2010 American Chemical Society