To shed light on the reaction mechanism, a series of control experiments were carried out. First, the radical nature of the reaction was confirmed through a radical trapping experiment. When 2.0 equivalent of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) was introduced into the reaction mixture, the reaction was completely halted, and the TEMPO adduct 9 was detected. In addition, 1,1-diphenylethene was also demonstrated to be a good radical capture reagent to give adduct 10 in an excellent 97% yield (Fig. ). Then, a deuterium labeling experiment was performed. When the reaction was carried out in the presence of 5 equiv of D2O, we isolated an 18% yield of the deuterium product 3aa' alongside a 71% yield of 3aa. Conversely, treating of 3aa with D2O under the standard conditions did not result in any deuterium labelling, suggesting that H/D exchange of product 3aa