Simple isotope labelling

Tritiation, the introduction of ³H into molecules, is an important tool to label and study the behaviour and properties of bioactive molecules in an animal or organism. Here, Tobias Ritter and colleagues report a Pd-catalyzed process for selectively introducing both ³H and deuterium, ²H, into aromatic organic compounds. This approach uses tritium gas, which is less toxic and of higher isotopic purity than the more commonly-used tritiated water. It makes use of aryl thianthrenium salts, overcoming a key limitation of the common aryl halide electrophiles, which are incompatible with dihydrogen.