Diamine Derivatives Containing Imidazolidinylidene Propanedinitrile as a New Class of Histamine H3 Receptor Antagonists: Conformationally Restricted Derivatives.

Novel conformationally restricted diamine derivatives containing imidazolidinylidene propanedinitrile were synthesized and evaluated for human and rat histamine H3 receptor (H3R) binding affinities. Among them, compounds 2b, 2c, 2j, 2k and 2m were found to be potent ligands for both H3Rs with Ki values in the sub-nanomolar range, and showed potent H3 receptor antagonism.