Synthesis of radioiodinated N-succinimidyl iodobenzoate: optimization for use in antibody labelling

N-succinimidyl-3-(tri-n-butylstannyl)benzoate (m-BuATE), N-succinimidyl-3-(tri-methylstannyl)benzoate (m-MeATE) and N-succinimidyl-4-(tri-n-butylstannyl)benzoate (p-BuATE) were synthesized and radioiodinated using either N-chlorosuccinimide (NCS) or t-butylhydroperoxide (TBHP) as the oxidant. Radiohalogenation of m-MeATE proceeded more rapidly than m-BuATE. NCS was the more efficient oxidant at reaction times less than 15 min; use of both TBHP and NCS resulted in nearly quantitative yields after 15 min when m-MeATE was used. Using NCS, achieving optimal antibody coupling and specific binding required purification of the active ester by HPLC; in contrast, with TBHP, only Sep-Pak purification was needed.