Synthesis of carbon-14 labelled moxifloxacin hydrochloride

For studies of pharmacokinetics and metabolism of the new antiinfective mox ifloxacin, the corresponding carbon-14 labelled substance was required. Sta rting from the appropriately substituted benzoic acid chloride and diethyl [2-C-14]malonate, a 7-step synthesis and the final crystallisation of the h ydrochloride led to [C-14]moxifloxacin hydrochloride, labelled in position 3 of the quinolone ring system. Two radiosyntheses were performed leading t o 0.108 g (0.340 GBq) of the labelled product in the first and 0.729 g (2.1 43 GBq) of the labelled product in the second synthesis.