structure‐activity relationships among histamine H3‐receptor antagonists the imidazole ring of known H3‐receptor antagonists was replaced by different heteroaromatic ring systems. Thus, azines and diazines with ether (6–13) and carbamate (15–24) moieties as functional groups were synthesized. The obtained compounds did not show significant H3‐receptor antagonist activity in vitro (rat brain cortex) or