title: 3 Beta-(p-trimethylsilylphenyl)tropane-2 beta-carboxylic acid methyl ester: a new precursor for the preparation of [123I]RTI-55.
abstract: Here we report the synthesis of 3 beta-(p-trimethylsilylphenyl)tropane-2 beta-carboxylic acid methyl ester, a new, easily prepared precursor for the synthesis of radioiodinated versions of RTI-55. In contrast to the 3 beta-(p-trimethylstannylated) precursor for radioiodination, the aryl silane is prepared directly by the 1,4 addition of p-trimethylsilylphenylmagnesium iodide to anhydroecgonine methyl ester in 49% yield (Scheme 1). Radioiododesilylation proceeded smoothly (approx. 85% radioincorporation after 15 min at room temperature) using 1 microgram of the novel precursor in trifluoroacetic acid and chloramine-T as oxidant. Isolated radiochemical yields for 125I and 123I radiolabelings were 72 and 48%, respectively, with a calculated specific activity for [123I]RTI-55 of > 2000 mCi/mumol.
authors.affiliation: Division of Nuclear Medicine Sciences, Johns Hopkins Medical Institutions, Baltimore, MD 21205-2179, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Musachio
authors.forename: K I
authors.initials: KI
authors.lastname: Keverline
authors.forename: F I
authors.initials: FI
authors.lastname: Carroll
authors.forename: R F
authors.initials: RF
authors.lastname: Dannals
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003042:Cocaine / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D007457:Iodine Radioisotopes / Q000737:chemistry*; D007553:Isotope Labeling / Q000379:methods; D014297:Trimethylsilyl Compounds / Q000138:chemical synthesis*; D014326:Tropanes / Q000138:chemical synthesis*
chemical_list: C098213:3-(4-trimethylsilylphenyl)tropane-2-carboxylic acid methyl ester; D007457:Iodine Radioisotopes; D014297:Trimethylsilyl Compounds; D014326:Tropanes; C069723:2beta-carbomethoxy-3beta-(4-iodophenyl)tropane; D003042:Cocaine