New cis-, trans-2-butene and 1, 2-bismethylbenzene analogues of MM77 and NAN-190 (1- {4-[4-(2-methoxyphenyl)-piperazin-1-yl]-butyl}-pyrrolidine-2, 5-dione and isoindole-1, 3- dione, respectively) were synthesized. The differences in their in vitro affinity for serotonin 5- HT7 and 5-HT1A receptors were explained using a conformational analysis. A bioactive conformation of those compounds for the 5-HT7 receptor, different from that established ...