The Gouverneur group has pioneered catalysis of this type of late-stage reaction by copper (III) (“three”) or palladium (IV) (“four”) via a Chan-Lam mechanism. The only enzyme that catalyzes this type of reaction was discovered in S. cattleya in 2002 and performs it on SAM. In a copper-free Sandmeyer-like mechanism, anilines undergo (-5[1])this transformation by reacting with (-5[1])nitrous acid and then a weakly coordinating anion. Since DAST often explodes, Sigma-Aldrich now recommends that this reaction can be safely (15[1])performed in air using a DABCO derivative (15[1])prefixed (*) “select.” (10[1])Roughly (10[1])half (10[1])of all small-molecule drugs undergo this modification, which turns uracil into (10[1])a chemotherapeutic and converts (10[1])deoxyglucose into a PET tracer. For 10 points, name this reaction that adds the most electronegative element to a molecule. (10[1])■END■ (10[2])