No-carrier-added (4-fluoro-3-[131I]iodobenzyl)guanidine and (3-[211At]astato-4-fluorobenzyl)guanidine

Bioconjug Chem. 1996 Jan-Feb;7(1):102-7. doi: 10.1021/bc950078i.


With 3-bromo-4-fluorotoluene as starting material, [4-fluoro-3-(trimethylsilyl)benzyl]guanidine was prepared in five steps in 1.5% overall yield. Radioiodination of this silicon precursor using N-chlorosuccinimide in trifluoroacetic acid at room temperature for 5 min gave (4-fluoro-3-[131I]-iodobenzyl)guanidine ([131I]FIBG) in 50-60% radiochemical yield. A byproduct which had a retention time in two HPLC systems similar to that of (m-iodobenzyl)guanidine (MIBG) was formed in about 30% yield. [131I]FIBG was stable up to 3 h under these conditions of iodination, indicating that the byproduct is not generated as a result of [131I]FIBG degradation. Using hydrogen peroxide as the oxidant in aqueous medium and a reaction time of 30 min at 50 degrees C, yields of [131I]FIBG could be increased to 75-80%, with less than 7% of the byproduct formed under these conditions. Astatination of the silicon precursor using N-chlorosuccinimide in trifluoroacetic acid at 70 degrees C gave 65-70% radiochemical yield of (3-[211At]astato-4-fluorobenzyl)guanidine ([211At]AFBG) in 10-15 min; about 17% of the byproduct formation was seen. Astatination of the silicon precursor under aqueous conditions using hydrogen peroxide was not successful.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acids*
  • Cell Line
  • Chromatography, High Pressure Liquid
  • Guanidines / chemical synthesis*
  • Guanidines / metabolism
  • Humans
  • Indicators and Reagents
  • Iodine Radioisotopes*
  • Iodobenzenes / chemical synthesis*
  • Iodobenzenes / metabolism
  • Isotope Labeling / methods
  • Neuroblastoma
  • Tumor Cells, Cultured


  • Amino Acids
  • Guanidines
  • Indicators and Reagents
  • Iodine Radioisotopes
  • Iodobenzenes
  • 1-(3-astatobenzyl)guanidine
  • (4-fluoro-3-iodobenzyl)guanidine
  • statine