Synthesis and evaluation of a novel samarium-153 bifunctional chelating agent for radioimmunotargeting applications

A new bifunctional chelating agent (BCA), 3‐(4‐isothiocyanatobenzyl)triethylenetetraaminehexaacetic acid (9), has been synthesized in fast and easy conditions. An improved synthesis of its position isomer 1‐(4‐isothiocyanatobenzyl)triethylenetetraaminehexaacetic acid (19) is also described. Stability in serum media of the two corresponding aminobenzyl derivatives‐samarium‐153 complexes, respectively, 3‐(4‐aminobenzyl)triethylenetetraaminehexaacetic acid—samarium‐153 and 1‐(4‐aminobenzyl)triethylenetetraaminehexaacetic acid—samarium‐153, have been evaluated. The 3‐(4‐aminobenzyl)triethylenetetraaminehexaacetic acid complex revealed excellent stability in serum media, and therefore 3‐(4‐isothiocyanatobenzyl)triethylenetetraaminehexaacetic acid (9) appears useful for future in vivo radioimmunotherapy investigations. Copyright © 2005 John Wiley & Sons, Ltd.