Development of [ 11C]L-159,884: A radiolabelled, nonpeptide angiotensin II antagonist that is useful for angiotensin II, AT 1 receptor imaging

Abstract

[ 11C]L-159,884 ([ 11C] N-[[4′[(2-ethyl-5,7-dimethyl-3H-imidazo[4,5-b]pyridin-3-yl) methyl][1,1′- biphenyl]-2-yl]sulfonyl]-4-methoxybenzamide) and [ 11 C]L-162, 574 ([ 11 C] N-[[4′[2- ethyl-5,7- dimethyl-3 H-imidazo[4,5- b]pyridin-3- yl)methyl][1,1′- biphenyl]-2- yl] sulfonyl]-3- methoxybenzamide) , b both potent and selective ligands for the AT 1 receptor, were prepared by C-11 methylation of the corresponding desmethyl phenolic precursors. The radiotracers were purified by semi-preparative reverse-phase HPLC. Non-decay corrected radiochemical yields were 5 and 3% for L-159,884 and L-162,574 respectively, and the average specific activity was 2979 mCi/μmol at end-of-synthesis (EOS). The average time of synthesis was 18 min.