Benzene Ring Functionalization of Indoles by Iterative Directed peri and ortho Lithiation

Significance

Benzene ring functionalized indole derivatives are normally prepared by electrophilic substitution and via use of substituted aromatic precursors for terminal indole ring construction by classical methods, e.g. Fischer indole, Leimgruber-Bacho reactions. The reported directed peri- and ortho-metalation methodology allows regio­selective C-4 substitution based on the CH₂NR₂- directed metalation group (DMG) previously developed by Iwao. The introduced NHBoc DMG is used for further C-5 functionalization in modest to very good yields.