Halogen bonding assisted site-selective C-3 triaryl methylation of indoles and N-triaryl methylation of imidazoles
Dipika Konwar1, Pranamika Sarma2, Jagat Chandra Borah2
1Department of Chemical Sciences, Tezpur University, Napaam-784028, Assam, India. utbora@yahoo.co.in.
Abstract:
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.
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