Tritium labelling and characterization of the antimalarial drug (+/−)-chloroquine by several methods

To study its mechanism of antimalarial action, a tritium labelled analogue of (+/−)-chloroquine was required at high specific activity. Two synthetic methods were successfully employed. [3-3H] (+/−)-Chloroquine 2 was prepared by the catalytic tritium dehalogenation of an iodo precursor and [N-ethyl-3H] (+/−)-chloroquine 4 was synthesized by the alkylation of (+/−)-desethylchloroquine with [3H] ethyl iodide.