[Synthesis and pharmacodynamic activity of 2-(3-(2-phenylethyl)benzofuran-2-yl)-N-propyl-ethanamine]

The benzofuranethanamines 3a and 3b were synthesized and pharmacologically tested to investigate structure-activity relationships with antiarrhythmic compounds. The key-step in the synthesis was the chemoselective reduction of the chloroacetyl-dihydrobenzofurane 5 to chloroethylbenzofurane 9 using triethylsilane/BF3.Et2O. Results of a series of further attempts to reduce 5 are also described. Pharmacological investigations on isolated guinea pig heart muscle preparations showed that 3a exhibits similar negative inotropic and negative chronotropic action in comparison to propafenone and the conformationally restricted benzofurane 1a. In contrast to these substances, however, 3a shows no beta 1-adrenoreceptor blocking activity.