Dihydropyrrolopyrazole transforming growth factor-beta type I receptor kinase domain inhibitors: a novel benzimidazole series with selectivity versus transforming growth factor-beta type II receptor kinase and mixed lineage kinase-7.

Novel dihydropyrrolopyrazole-substituted benzimidazoles were synthesized and evaluated in vitro as inhibitors of transforming growth factor-beta type I receptor (TGF-beta RI), TGF-beta RII, and mixed lineage kinase-7 (MLK-7). These compounds were found to be potent TGF-beta RI inhibitors and selective versus TGF-beta RII and MLK-7 kinases. Benzimidazole derivative 8b was active in an in vivo target (TGF-beta RI) inhibition assay.