Metal-Free Regioselective Hypervalent Iodine-Mediated C‑2 and C‑3 Difunctionalization of <i>N</i>‑Substituted Indoles

Mild, metal-free, highly regioselective hypervalent-iodine mediated C-2 acetoxylation and C-3 oxidations of N-substituted indoles with (diacetoxyiodo)­benzene [PhI­(OAc)2] have been reported. The reaction involves three cascade steps. The quantity of PhI­(OAc)2 employed in this reaction plays a key role in the outcome of three types of products (2a–4a). Furthermore, the mild and highly regioselective C-2 oxidation and C-3 dichlorination of N-substituted indoles with PhICl2 have been developed. Extensive studies including in situ IR techniques and H2O18-labeling experiment were performed to gain insight into the possible reaction mechanism.