Reactive derivative of adenosine‐5′‐triphosphate formed by irradiation of ATP γ‐p‐azidoanilide

UV and 1H NMR spectra changes demonstrate that p‐azidoanilides of ATP, ITP, pyrophosphate after irradiation at 313 nm, transform to similar reactive intermediates. The latter react readily with morpholine, iso‐propylamine, tert‐butylamine, imidazole, mercaptoethanol the reactivity being qualitatively correlated with nucleophilicity. By analogy with the transformation of p‐azidoanilide, it is concluded that the reactive intermediate is the respective derivative of quinone diimine. Photoaffinity labelling of proteins with p‐azidoanilide derivatives may proceed as the reaction of the nucleophilic centers of proteins with this quinone diimine derivative, rather than as a direct attack by a nitrene biradical.