A CONVENIENT, NOVEL-APPROACH FOR THE SYNTHESIS OF POLYAZA MACROCYCLICBIFUNCTIONAL CHELATING-AGENTS

The convenient, synthetically useful bifunctional chelating agents, yl )-1,4,7,10-tetraazacyclododecan-1,4,7-triacetate (p-ABz-DO3A) 3 and am inobenzyl)-1,4,8,11-tehaazacyclotetradecane-1,4, 8-triacetate (p-ABz-T E3A) 6, were obtained by reaction of an ethyl bromoacetate with 1,4,7, 10-tetraazacyclododecane and 1,4,8,11-tetraazacyclotetradecane followe d by reaction with nitrobenzyl bromide. This method proved more effici ent than any described in the literature since the overall yield in a two-step synthesis sequence starting from tetraazamacrocycles was 68%. Copyright (C) 1996 Published by Elsevier Science Ltd