“Back‐to‐Front” Indole and Carbazole Synthesis from <i>N,N</i> ‐Bis‐(2‐bromoallyl)amines by Combining Carbolithiation Reactions with Gold‐Catalysis

The combination of organolithium chemistry with gold catalysis has enabled the development a synthetic strategy for accessing polysubstituted indoles and carbazoles from readily available starting materials. This method is based on “back-to-front” approach ketopyrroles, generated by intramolecular carbolithiation N,N-bis-(2-lithioallyl)amines that evolve into 3,4-bis(lithiomethyl)dihydropyrrole intermediates capable reacting carboxylic esters Weinreb amides. These ketopyrroles have demonstrated to be excellent precursors mono or bis(alkynols)pyrroles that, under gold-catalysis, experience benzannulation reaction providing access regioselectively substituted carbazoles.