Synthesis and anxiolytic activity of N-substituted cyclic imides (1R*,2S*,3R*,4S*)-N-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-2,3- bicyclo[2.2.1]heptanedicarboximide (tandospirone) and related compounds.

A series of cyclic imides bearing a omega-(4-aryl and 4-heteroaryl-1-piperazinyl)alkyl moieties was synthesized and tested in vivo for anxiolytic activity. The in vitro binding affinities of these compounds were also examined for 5-HT1A receptor sites. Structure-activity relationships within these series are discussed. One of these compounds, (1R*,2S*,-3R*,4S*)-N-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-2,3- bicyclo[2.2.1]heptanedicarboximide (1: tandospirone), was found to be equipotent with buspirone in its anxiolytic activity and more anxio-selective than buspirone and diazepam. Tandospirone (1) is currently undergoing clinical evaluation as a selective anxiolytic agent.