title: Synthesis and dopamine receptor affinities of 2-(4-fluoro-3- hydroxyphenyl)ethylamine and N-substituted derivatives.
abstract: The synthesis of 2-(4-fluoro-3-hydroxyphenyl)ethylamine (26) and of some N,N-dialkyl derivatives (27-30) starting from 4-fluoro-3-hydroxytoluene and their in vitro binding affinities for dopamine (DA) receptor are reported. The amine 26 can be regarded as a molecular modification of DA in which the para hydroxyl group is replaced by fluorine. The new compounds 26-30 were evaluated for their affinity at D-1 and D-2 DA receptor subtypes by displacement of [3H]SCH 23390 (D-1 selective) and [3H]spiperone (D-2 selective). The amine 26 had about 2-fold less affinity for D-1 and D-2 binding sites than DA. The substitution of the amino group with ethyl, n-propyl, and 2-phenylethyl groups decreased the affinity for D-1 binding sites but greatly enhanced the effectiveness on D-2 binding sites. The N-ethyl- (28) and N-n-propyl-N-(2-phenylethyl)-2-(4-fluoro-3- hydroxyphenyl)ethylamine (30) were the most potent members of the series with high selectivity for D-2 binding sites. A similar effect was observed with isomeric N-n-propyl-N-(2-phenylethyl)-2-(3-fluoro-4-hydroxyphenyl)ethylamine (31) which was approximately 65 times more selective for D-2 sites vs D-1 sites. The introduction of a 2-phenylethyl group on the nitrogen atom induce the highest effect, perhaps as a consequence of an increased liposolubility or of binding to a complementary lipophilic site on the receptor.
authors.affiliation: Department of Chemical Sciences, University of Camerino, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Claudi
authors.forename: M
authors.initials: M
authors.lastname: Cardellini
authors.forename: G M
authors.initials: GM
authors.lastname: Cingolani
authors.forename: A
authors.initials: A
authors.lastname: Piergentili
authors.forename: G
authors.initials: G
authors.lastname: Peruzzi
authors.forename: W
authors.initials: W
authors.lastname: Balduini
mesh_terms: D000818:Animals; D001552:Benzazepines / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D015259:Dopamine Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D018492:Dopamine Antagonists; D010627:Phenethylamines / Q000138:chemical synthesis* / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects; D013329:Structure-Activity Relationship
chemical_list: D001552:Benzazepines; D015259:Dopamine Agents; D018492:Dopamine Antagonists; D010627:Phenethylamines; D011954:Receptors, Dopamine