1-(4-Cyclopentylphenyl)piperazine and its 4-substituted derivatives; Synthesis and biological screening

Abstract

Heating the hydrochlorides of 4-cyclopentylaniline and diethanolamine to 250 °C gave 1-(4-cyclopentylphenyl)piperazine (I). Acylation of I with ethyl formate and the corresponding acyl chlorides gave the amides II, VI, and VII which were reduced with lithium aluminium hydride to the piperazines III, VIII, and IX. Treatment of I with benzyl chloride and with 4-chloro-1-(4-fluorophenyl)butan-1-one under different conditions led to compounds IX and XI. Addition reaction of I to 1,2-epoxybutane resulted in the amino alcohol V. The products showed marginal tranquillizing activity (especially compound VIII), some antimicrobial activity in vitro and some anthelmintic activity.