Halogen bonding assisted site-selective C-3 triaryl methylation of indoles and N -triaryl methylation of imidazoles.

Halogen bonding triggered by the Lewis basic nature of acetonitrile catalyzes the site-selective C-3 triaryl methylation of indoles and N -triaryl methylation of imidazoles with trityl chlorides under catalyst-, metal-, and additive-free conditions at room temperature. This method generates a quaternary carbon centre appended to a heterocyclic moiety. UV-Vis and FT-IR analyses indicate the existence of halogen bonding which is the driving force of the reaction. This approach is suitable for a wide range of substrates, furnishing moderate to excellent yields (up to 100%) of triaryl methylated products under ambient reaction conditions. Equimolar amounts of reactants are sufficient to obtain the optimum yield and in some cases pure products can be obtained without column chromatography.