Mechanistic Studies. A series of control experiments and spectroscopic investigations were conducted to elucidate the reaction mechanisms (Figure ). In the absence of Fe catalysts, no product 4a or Ritter-type amination product 104 were detected, ruling out the possibility of a radical-polar crossover and subsequent carbocation trapping pathway (Figure , i). When iron-complex 105, which was prepared from FeSO4•H2O, 4-picoline and NaN3 in water, 22 was subjected to the standard reaction conditions with DBT salt 4a and styrene, the desired product 4 was obtained in 79% NMR yield (Figure 5A, ii). This result highlights the importance of the iron catalyst in both the photo-catalyzed DBT salt reduction and the azidation step; however, further investigation is necessary to fully comprehend its role in these processes. Additionally, a radical clock experiment using cyclopropyl styrene 106 under the standard conditions led to the formation of ring-opened product 108 in 45% isolated yield. This result confirms the generation of aryl radical from DBT salt and its subsequent addition to styrene, which formed radical intermediate 107 through the radical ring opening of the cyclopropyl group (Figure ). To further establish the light-dependency of this reaction, an intermittent illumination experiment was performed, and the results demonstrated a clear correlation between irradiation and productivity (Figure ). Importantly, no product formation was observed during the dark phase, eliminating the possibility of any thermal processes and firmly establishing that the reaction is specifically triggered by light. This observation also underscores the crucial role of photocatalyst fac-Ir(ppy)3 in facilitating the reaction. Additionally, Stern-Volmer luminescence quenching studies using DBT salt 4a as the analyte revealed quenching of the excited photocatalyst, providing evidence for electron transfer between DBT salts and the excited photocatalyst (Figure ). Based on the experimental findings and previous literatures, 12f,12i,18 a tentative mechanism is proposed as depicted in