Synthesis and Evaluation of 2‐(5‐Methoxythiophen‐3‐yl)ethylamines as Potential Dopamine Agonists.

Abstract The synthesis of 2-(5-methoxythiophen-3-yl)ethylamine and some derivatives bearing propyl and 2-phenylethyl substituents on the amino group has been described. The affinities for dopamine D 1 and D 2 receptors were evaluated by binding assays on rat striatum. None of the compounds show affinity for the D 1 receptor. In the D 2 binding assays the N -propyl- N -(2-phenylethyl) derivatives show affinity similar to that of the reference compound N-n -propyl- N -(2-phenylethyl)-2-(3-hydroxyphenyl)ethylamine ( 1 , RU 24213). In preliminary behavioral tests [2-(5-methoxythiophen-3-yl)ethyl]phenethylpropylamine behaves as a selective D 2 agonist.