Rapid route to 3,4-substituted indoles via a directed ortho metalation-retro-Mannich sequence.

[reaction: see text] In the presence of NXS (X = Br, I, Cl), gramine derivatives 1, derived by combined directed ortho metalation (DoM)-cross-coupling sequences, rapidly undergo retro-Mannich fragmentation (2) to afford 3-halo indoles 3 in 37-88% yields. A conceptually new methodology to diverse 3,4-substituted indoles (10, 11, 13) is thereby introduced.