Silver-Catalyzed Remote C5–H Selenylation of Indoles

Remote
C–H functionalization at C5 is the most sparingly
observed selectivity in the functionalization of indole templates.
Herein, we reported that the combination of a AgSbF6 catalyst
and phenyliodine diacetate oxidation enabled the C–H selenylation
at the C5 position of indole scaffolds in a selective version, thus
leading to the formation of a wide scope of 5-selenylated indole derivatives,
which are otherwise difficult to prepare. Mechanistic studies indicated
that current transformation follows a radical process, and the tethered
C3 pivaloyl group on indole scaffolds plays roles in both blocking
the active C3 position and manipulating the electronic affinity of
the arenes.