SYNTHESIS OF TRITIUM LABELED OXIMES - 2-PYRIDINE ALDOXIME METHIODIDE (2-PAM) AND 1-(2-HYDROXYIMINOMETHYLPYRIDINIUM)-1-(4-CARBOXYAMIDOPYRIDINIUM)DIMETHYLETHER DICHLORIDE (HI-6), WITH HIGH SPECIFIC ACTIVITY

Synthesis of two quaternary pyridinium oximes [H-3]2-PAM and [H-3]HI-6 (18 and 22 Ci/mmole, respectively) was performed by using unlabelled 6-bromo 2-pyridine aldehyde (I) as a common starting material. The labelling was based on a catalytic ring-tritiation of 6-bromo 2-diethylketal pyridine followed by acid hydrolysis and reaction with hydroxylamine to yield 6-[H-3]2-hydroxyiminomethyl pyridine (II). [H-3]2-PAM was obtained by reacting II with methyliodide and [H-3]HI-6 was prepared by alkylation of II with bischlorodimethylether followed by coupling to isonicotineamide. The radiochemical purity of [H-3]2-PAM and [H-3]HI-6 was 98% and at least 95%, respectively.