Synthesis of 75Se‐2‐phenyl‐1,2‐benzisoselenazol‐3(2H)‐one (PZ 51; ebselen. A novel biologically active organo‐selenium compound

The preparation of 75Se‐ebselen (75Se‐PZ 51) in a high radiochemical yield (∼40 %) and with a specific activity of 240 mCi/mM (8.9 GBq/mM) is described. It entails a very simple, fast and one‐pot procedure starting from elemental 75Se‐selenium. 75Se‐diselenosalicylic acid 4 is initially prepared as the key intermediate which is transformed into a corresponding dichloride 5‐before reacting with aniline to yield the desired 75Se‐ebselen. Identity and purity of the labelled compound were controlled by comparison in TLC, HPLC and MS with an authentic sample (1‐2).