Visible-light-mediated C2-amination of thiophenes by using DDQ as an organophotocatalyst.

In this work, a direct C-H activation of thiophenes was presented via an oxidation pathway under visible-light irradiation, in which the thiophene radical cation serves as the key intermediate. Various thiophenes and azoles could be transformed into the corresponding amination products well, and HO was the only byproduct which is environmentally benign. Our results showed that tert-butyl nitrite (TBN) served as the electron transfer mediator and O as the terminal oxidant to regenerate the photocatalyst DDQ and revive the photocatalytic cycle.