Tritiated compounds play a vital role in pharmaceutical research, as they can be used as a radiotracer for absorption, distribution, metabolism, and excretion (ADME) studies. 45,48,54 Hence, we showcased the applicability of our protocol for the site-selective tritiation in one example (Fig. ). In this case, an excellent selectivity together with high tritium incorporation was observed. Reaction conditions: a 6.7 μmol substrate, 5 mol% PC (3DPA2FBN), 3 eq. K2CO3, 5 eq. T2O, 100 µL DMF, 451 nm, 18 °C, 17 h, isolated yields. Please see SI for detailed procedure.