Scheme 1
Radiosynthesis of [44Sc]3. The DOTA-functionalized Tz (1) was added to a solution of 44ScCl3 in ammonium acetate (pH 4) and ethanol. The solution was heated to 95 °C for 10 min. After cooling to room temperature, the solution was loaded on to an SPE column, flushed with water, and the pure product eluted with ethanol. [44Sc]3 was obtained in 85–95% RCY and > 99% RCP.