Succinimide derivatives. II. Synthesis and antipsychotic activity of N-[4-[4-(1,2-benzisothiazol-3-yl)-1-piperazinyl]butyl]-1,2-cis- cyclohexanedicarboximide (SM-9018) and related compounds.

Cyclic imides bearing omega-(4-benzisothiazol-3-yl-1-piperazinyl)alkyl moieties were synthesized and tested for antipsychotic activity. The in vitro binding affinities of these compounds were examined for dopamine 2 (D2) and serotonin 2 (5-HT2) receptor sites. Structure-activity relationships within these series are discussed. One of these compounds, N-[4-[4-(1,2-benzisothiazol-3-yl)-1-piperazinyl]butyl]-1,2-cis- cyclohexamedicarboximide (SM-9018), was found to be more potent and more selective in vivo than tiospirone in its antipsychotic activity. SM-9018 (17) is currently undergoing clinical evaluation as a selective antipsychotic agent.