Conformational analysis of 2-[2-(3-methoxyphenyl) ethyl]phenoxyalkylamines with high 5-HT2 receptor binding affinity.

A conformational analysis of three groups of 2-[2-(3-methoxyphenyl)ethyl]phenoxyalkylamines with high 5-HT2 receptor binding affinity has been performed using the systematic search. Two groups of compounds with different lengths of alkyl chains connecting the amine nitrogen and the central oxygen showed a one order difference in their 5-HT2 receptor binding affinity. The computational analysis of these compounds confirmed the differences in the N--O distances between the two groups, quantitatively. A probable active conformation was proposed based on a superimposition of the stable conformations over a rigid molecule, mianserin. Two hydroxy derivatives in the third group showed a significant difference in their binding affinity depending on the stereochemistry of the hydroxy group. The difference in the energetically favorable order of the stable conformations reasonably explained the relationship between the stereochemistry and the binding activity. A molecular dynamics-based conformational search was also carried out to compare it with the systematic search.