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

Abstract

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.