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

Abstract

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