SELECTIVE ARYLATION OF TERTIARY AMINES TO N-ARYL QUATERNARY AMMONIUM SALTS

Maayan Hirsch, Schulich Faculty of Chemistry, Technion, Haifa, Israel
Charles Diesendruck, Schulich Faculty of Chemistry, Technion, Haifa, Israel

Quaternary ammonium salts have countless uses, such as phase-transfer catalysts and anion-exchange membranes, and constitute biologically relevant functional groups, playing important roles in alkylation reactions and in natural products. Few examples of nucleophilic aromatic substitutions by tertiary amines are found in the literature, and those demand harsh reaction conditions and electron poor reagents. We describe the use of reactive phenyl cations to produce the intended products under mild conditions. However, these reactive species tend to undergo competitive Friedel-Crafts additions, limiting the selectivity of the reaction. Chemoselectivity of the phenyl cation intermediates is improved using reduced temperatures or an organometallic system.