No-carrier-added (4-fluoro-3-[131I]iodobenzyl)guanidine and (3-[211At]astato-4-fluorobenzyl)guanidine.
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.
Vaidyanathan
G
G
Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA.
Affleck
D J
DJ
Zalutsky
M R
MR
D000596:Amino Acids; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D006146:Guanidines / Q000138:chemical synthesis* / Q000378:metabolism; D006801:Humans; D007202:Indicators and Reagents; D007457:Iodine Radioisotopes; D007462:Iodobenzenes / Q000138:chemical synthesis* / Q000378:metabolism; D007553:Isotope Labeling / Q000379:methods; D009447:Neuroblastoma; D014407:Tumor Cells, Cultured
D000596:Amino Acids; D006146:Guanidines; D007202:Indicators and Reagents; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; C078685:1-(3-astatobenzyl)guanidine; C090053:(4-fluoro-3-iodobenzyl)guanidine; C013165:statine