Medicinal chemistry 2013-04-01

Synthesis and 1 Receptor Binding of Halogenated N,N'-Diphenethylethylenediamines.

JonathanM Fitzsimmons, JohnR Lever, SusanZ Lever

Index: Med. Chem. (Los Angeles) 1(102) , (2011)

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Abstract

Eight halogenated N,N'-diphenethylethylenediamines were synthesized, characterized and evaluated for 1 receptor binding affinity in vitro. Measurements of lipophilicity also were obtained. The substitution pattern on one of the aromatic rings remained constant as 3,4-dichloro, while the substituents on the other aromatic ring were varied to include fluorine, bromine or iodine in either the 2-, 3- or 4- positions. Two main structure activity relationships were observed. First, halogen substitution on the 3- or 4-positions of the aromatic ring conferred higher binding affinities (K i values 6.35 - 15.82 nM) than the corresponding substitutions at the 2-position (K i values 12.08 - 43.15 nM). Second, derivatives containing either a bromo or fluoro substituent at a given position showed higher 1 receptor binding affinities than derivatives with a corresponding iodo substituent. The data indicate that 1 receptor affinity for this structural series is sensitive to steric bulk at the 2-position. Log k'w measurements for the halogenated N,N'-diphenethylethylenediamines were determined by high performance liquid chromatography, and varied from 2.54 - 3.71. In particular, the 3-fluoro analog exhibited a log k'w = 2.54 accompanied by a 1 receptor K i = 7.8 nM. These novel N,N'-diphenethylethylenediamines warrant further investigation in behavioral assays, and radiolabeled versions may prove suitable for in vivo studies of 1 receptors.