The reaction of nucleophilic species with quinonoid 6,6,7,7-tetramethyldihydropterin

The products, kinetics, and mechanisms for the reaction of HO^-, NH₂OCH₃, and HOCl with 1,5-quinonoid 6,6,7,7-tetramethyldihydropterin are provided. The reaction with hydroxide leads to a rearranged imidazolone whose structure was proved by independent synthesis. With methoxylamine the product is a dihydro adduct derived from methoxylamine displacement of the 2-amino group. In this case the structure of the product was obtained via X-ray crystallography and ¹³C NMR with the former providing novel information about the tautomeric form of this pterin quinonoid species. The chlorination of the quinonoid generates N2 or N3 chloroamines based on high-resolution mass spectrometric analysis. Mechanisms for these transformations are proposed.