855658-69-4Relevant articles and documents
Ring-substituted histaprodifen analogues as partial agonists for histamine H1 receptors: Synthesis and structure-activity relationships
Elz, Sigurd,Kramer, Kai,Leschke, Christian,Schunack, Walter
, p. 41 - 52 (2007/10/03)
Thirteen racemic benzene ring-substituted analogues of histaprodifen (8a; 2-[2-(3,3-diphenylpropyl)-1H-imidazol-4-yl]ethanamine), a novel lead for potent and selective histamine H1-receptor agonists, have been prepared from substituted 4,4-diphenylbutyronitriles 5 via cyclization of the corresponding methyl butyrimidates 6 with 2-oxo-4-phthalimido-1-butyl acetate in liquid ammonia, followed by deprotection. Nitriles 5 were accessible by alkylation of either substituted diphenylmethanes with 3-bromopropionitrile or diethyl malonate with substituted 1-chloro-diphenylmethanes and subsequent standard reactions. The title compounds 8 displayed partial agonism on conctractile H1 receptors of the guinea-pig ileum (E(max) = 2-98% relative to histamine) and, compared with the endogenous agonist, were endowed with agonist potencies of 4-92%. The meta fluorinated (8c) and meta chlorinated (8f) analogues showed the highest relative potency in this series (95% confidence limits 85-99% and 78-102%), but did not exceed the value of the lead 8a (99- 124%). Compound 8c (2-[2-[3-(3-fluorophenyl)-3-phenylpropyl]-1H-imidazol-4- yl]ethanamine) was a partial agonist at contractile H1 receptors of the guinea-pig aorta (relative potency 154% vs. 100% for histamine) and at relaxation-mediating endothelial H1 receptors of the rat aorta (relative potency 556% vs. 100% for histamine) and matched with the functional behaviour of 8a. Agonism observed for each compound was sensitive to blockade by the selective H1-receptor antagonist mepyramine (pA2 ? 9 (guinea-pig) and pA2 ? 8 (rat aorta)). All histaprodifen analogues 8 stimulated neither histaminergic H2/H3 nor cholinergic M3 receptors. They displayed only low to moderate affinity for these sites (H2: pD'2 3/M3: pA2 1-receptor agonist, viz. 2- phenylhistamine. (C) 2000 Editions scientifiques et medicales Elsevier SAS.