Synthesis of deuterium and tritium labelled m‐aminolevamisole and levamisole

Abstract

Abstract Levamisole (LEV) is a widely used anti‐parasitic agent. In order to characterise the biochemical pharmacology of LEV in parasitic nematodes, [ 3 H]LEV and a more active analogue [ 3 H] m ‐aminolevamisole (MAL) have been prepared. Labelling was accomplished by tritiated water exchange of MAL under acid conditions. Multiple site labelling was achieved in the positions ortho and para to the amino group of MAL. Tritiation of MAL HCl in [ 3 H] 2 O was achieved at 103°C for 23 h. Crude [ 3 H]MAL was diazotised (hydrochloric acid and sodium nitrite) and deaminated (hypophosphorous acid) to effect the synthesis of [ 3 H]LEV. Products of both reactions were purified by preparative h.p.l.c. and characterised by h.p.l.c., t.l.c. and mass spectrometry. (Radiochemical yield was about 15% and purity >90%.) Specific activities of 39 Ci/mmol for [ 3 H]MAL and 37 Ci/mmol for [ 3 H]LEV were obtained.