SYNTHESIS OF C-13-LABELED AND C-14-LABELED 1192U90, AN ORTHO-AMINO BENZAMIDE WITH A PRECLINICAL ATYPICAL ANTIPSYCHOTIC PROFILE

Three isotopic forms of potential antipsychotic agent 1192U90 enzisoth iazol-3-yl)-1-piperazinyl)butyl)benzamide) were synthesized: one conta ining C-13-isotopes and two containing C-14-isotopes. The compound in which the ortho-amino benzamide ring is completely C-13-labeled was pr epared in a four-step sequence starting from [C-13(6)]aniline. The C-1 4-labeled compounds were prepared by methods analogous to those previo usly described for the unlabeled material. The key step involved the c ondensation of -(4-aminobutyl)-1-piperazinyl)-1,2-benzisothiazole with isatoic anhydride. The first C-14-labeled compound (3) was prepared f rom C-14-labeled (4-aminobutyl)-1-piperazinyl)-1,2-benzisothiazole, wh ile the second compound (4) derived its isotopic label from [C-14]isat oic anhydride. Compound 3 had a specific activity of 26.55 mCi/mmol, a radiochemical purity of 99.3%, and a radiochemical yield of 3.4% base d on 9. Compound 4 had a specific activity of 22.67 mCi/mmol and a rad iochemical purity of 99.2%.