NO-CARRIER-ADDED [I-123] (BETA-D-ARABINOFURANOSYL)-5(E)-(2-IODOVINYL)URACIL (IVARAU) - HIGH-YIELDING RADIOLABELING VIA ORGANOTIN AND EXCHANGE-REACTIONS

Organotin intermediates for IVaraU synthesis were obtained following t he reaction of -tri-O-toluyl-beta-D-arabinofuranosyl-5-iodouracil with (E)-1,2-bis(tri-(n-butyl) stannyl)ethene in the presence of catalytic (Ph(3) P)(2) PdCl2. A direct precursor for IVaraU, )-5-[2-tri-n-butyl stannylvinyl]-arabinosyluridine, reacted with [I-123]NaI (10 mCi) or a lternatively [I-125]NaI in the presence of methanol and chloramine T p roviding no-carrier-added (NCA) [I-123)I]IVaraU in a radiolabeling yie ld up to 97%; the product was recovered following reversed phase HPLC. Unlabeled IVaraU was prepared in five steps from arabinosyluridine vi a an organotin intermediate with an overall yield of 22%. An exchange radioiodination was also identified, based on accessible BrVaraU in th e presence of water and a cuprous ion catalyst. [I-123]Naa (up to 40 m Ci) or alternatively [I-125]NaI reacted under exchange conditions to g ive no-carrier-added [I-123,I-125]IVaraU in a radiolabeling yield of 9 3%; the product was recovered following reversed phase HPLC.