SYNTHESIS OF [C-14] LABELED 3-[N-(4-BROMOPHENYL)CARBAMOYL]-7-CHLORO-4-HYDROXYCOUMARIN AND 3-[N-[5-(TRIFLUOROMETHYL)-1,3,4-THIADIAZOL-2-YL]CARBAMOYL]-7-CHLORO-4-HYDROXYCOUMARIN

The novel [C-14]-labelled 3-carbamoyl-4-hydroxycoumarins were prepared in two steps from 4-chloro-acetylsalicyloyl chloride (3). The isotope was incorporated by the reaction of diethyl malonate-1,3-C-14 with 4-chloro-acetylsalicyloyl chloride (3). Subsequent condensation of the resulting 3-ethoxycarbonyl-4-hydroxy-7-chlorocoumarin (5a) with 4-bromoaniline gave 3-[N-(4-bromophenyl)carbamoyl]-7-chloro-4-hydroxycoumarin (1a) with a specific activity of 0.7 mCi/mmol. Condensation of (5a) with 2-amino-5-trifluoromethyl-1,3,4-thiadiazole gave 3-[N-[5-(trifluoromethyl)-1,3,4-thiadiazol-2-yl]carbamoyl]-7-chloro-4-hydroxycoumarin (2a) with a specific activity of 0.6 mCi/mmol.