Development of radioligands for the imaging of cardiac β-adrenoceptors using SPECT. Part I: Asymmetric synthesis and structural characterization of five new iodine-containing β-adrenoceptor antagonist derivatives

The asymmetric synthesis of a series of iodinated β-adrenoceptor ligands is described. One ligand, (S)-(−)-[1-(2-iodophenoxy)]-3′-( tert-butylamino)-2′-propanol (CYBL3), is based on the β-adrenoceptor antagonist penbutolol. The other ligands are N-iodovinyl and N-iodoaryl analogues of the β-adrenoceptor antagonist CGP12177. These have been synthesized from 2-amino-3-nitrophenol. Furthermore, radioiodinated [ 123I]CYBL3 and [ 123I](2′S,2″E)-[4-(3′-(1″,1″-dimethyl-3″-iodo-2″ propenylamino)-2′-hydroxy propoxy)]-benzimidazol-2-one have been prepared by radiolabelling the corresponding trialkyltin precursors using [ 123I]-NaI in the presence of hydrogen peroxide.