Synthesis of carbon-14 labelled (3-{[(Z)-5-chloro-2,3-dihydro-3-(hydroxy-2-thienylmethylene)-2-oxo-1H-indol-1-yle]carbonylamino}propyl)trimethylammonium chloride, a potential cartilage-targeted antirheumatic drug

A [C-14]-labelled form of (3-{[(Z)-5-chloro-2,3-dihydro-3-(hydroxy-2-thieny lmethylene)-2-oxo-1H-indol-1-yle]carbonylamino}propyl)trimethylammonium chl oride, a potential cartilage-targeted antirheumatic drug, was required for pharmacokinetic studies. This compound, labelled with [C-14] located in the C-3 methylene position, was prepared in four steps starting from N-[3-(dim ethylamino)propyl]-5-chloro-2,3-dihydro-2-oxo-1H-indole-1-carboxamide and 2 -thiophene-[C-14]carbonyl chloride, previously synthesized by a two-step se quence from barium [C-14]-carbonate and 2-thienyllithium. The desired produ ct was obtained with a specific activity of 359 MBq/mmol (9.7 mCi/mmol). Th e overall radiochemical yield was 50% based on barium [C-14]-carbonate.