Oxidation of an indole substrate by porphyrin iron() superoxide: relevance to indoleamine and tryptophan 2,3-dioxygenases

Reaction of Fe III (O 2 &z.rad; − )(TPP) with 2,3-dimethylindole at −40 °C gives the ring-opened, dioxygenated N -(2-acetyl-phenyl)-acetamide product. The reaction was monitored in situ by low-temperature UV-vis and 1 H NMR spectroscopies. This work demonstrates that a discrete iron( iii )(superoxo) porphyrin is competent to carry out indole oxidation, as proposed for the tryptophan and indoleamine 2,3-dioxygenases. Reaction of Fe III (O 2 &z.rad; − )(TPP) with 2,3-dimethylindole at low temperature leads to the ring-cleaved, dioxygenated product, N -(2-acetyl-phenyl)-acetamide, analogous to TDO/IDO enzymes.