Gd-TEMDO: Design, Synthesis, and MRI Application.

A simple Ugi tetrazole multicomponent reaction allows the synthesis of a novel macrocyclic cyclen derivative with four appendant tetrazole arms in just two steps in excellent yields. This ligand, called TEMDO, turns out to have a high complexation affinity with lanthanoid metals. Here we describe the design, synthesis, solid-state structure, binding constant, and some MRI applications of the Gd-TEMDO complex as the first example of a congeneric family of oligo-amino tetrazoles.